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39 commits

Author SHA1 Message Date
Gino Valente
2b4180ca8f
bevy_reflect: Function reflection terminology refactor (#14813)
# Objective

One of the changes in #14704 made `DynamicFunction` effectively the same
as `DynamicClosure<'static>`. This change meant that the de facto
function type would likely be `DynamicClosure<'static>` instead of the
intended `DynamicFunction`, since the former is much more flexible.

We _could_ explore ways of making `DynamicFunction` implement `Copy`
using some unsafe code, but it likely wouldn't be worth it. And users
would likely still reach for the convenience of
`DynamicClosure<'static>` over the copy-ability of `DynamicFunction`.

The goal of this PR is to fix this confusion between the two types.

## Solution

Firstly, the `DynamicFunction` type was removed. Again, it was no
different than `DynamicClosure<'static>` so it wasn't a huge deal to
remove.

Secondly, `DynamicClosure<'env>` and `DynamicClosureMut<'env>` were
renamed to `DynamicFunction<'env>` and `DynamicFunctionMut<'env>`,
respectively.

Yes, we still ultimately kept the naming of `DynamicFunction`, but
changed its behavior to that of `DynamicClosure<'env>`. We need a term
to refer to both functions and closures, and "function" was the best
option.


[Originally](https://discord.com/channels/691052431525675048/1002362493634629796/1274091992162242710),
I was going to go with "callable" as the replacement term to encompass
both functions and closures (e.g. `DynamciCallable<'env>`). However, it
was
[suggested](https://discord.com/channels/691052431525675048/1002362493634629796/1274653581777047625)
by @SkiFire13 that the simpler "function" term could be used instead.

While "callable" is perhaps the better umbrella term—being truly
ambiguous over functions and closures— "function" is more familiar, used
more often, easier to discover, and is subjectively just
"better-sounding".

## Testing

Most changes are purely swapping type names or updating documentation,
but you can verify everything still works by running the following
command:

```
cargo test --package bevy_reflect
```
2024-08-19 21:52:36 +00:00
radiish
6ab8767d3b
reflect: implement the unique reflect rfc (#7207)
# Objective

- Implements the [Unique Reflect
RFC](https://github.com/nicopap/rfcs/blob/bevy-reflect-api/rfcs/56-better-reflect.md).

## Solution

- Implements the RFC.
- This implementation differs in some ways from the RFC:
- In the RFC, it was suggested `Reflect: Any` but `PartialReflect:
?Any`. During initial implementation I tried this, but we assume the
`PartialReflect: 'static` in a lot of places and the changes required
crept out of the scope of this PR.
- `PartialReflect::try_into_reflect` originally returned `Option<Box<dyn
Reflect>>` but i changed this to `Result<Box<dyn Reflect>, Box<dyn
PartialReflect>>` since the method takes by value and otherwise there
would be no way to recover the type. `as_full` and `as_full_mut` both
still return `Option<&(mut) dyn Reflect>`.

---

## Changelog

- Added `PartialReflect`.
- `Reflect` is now a subtrait of `PartialReflect`.
- Moved most methods on `Reflect` to the new `PartialReflect`.
- Added `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect}`.
- Added `PartialReflect::{try_as_reflect, try_as_reflect_mut,
try_into_reflect}`.
- Added `<dyn PartialReflect>::{try_downcast_ref, try_downcast_mut,
try_downcast, try_take}` supplementing the methods on `dyn Reflect`.

## Migration Guide

- Most instances of `dyn Reflect` should be changed to `dyn
PartialReflect` which is less restrictive, however trait bounds should
generally stay as `T: Reflect`.
- The new `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect, try_as_reflect, try_as_reflect_mut,
try_into_reflect}` methods as well as `Reflect::{as_reflect,
as_reflect_mut, into_reflect}` will need to be implemented for manual
implementors of `Reflect`.

## Future Work

- This PR is designed to be followed up by another "Unique Reflect Phase
2" that addresses the following points:
- Investigate making serialization revolve around `Reflect` instead of
`PartialReflect`.
- [Remove the `try_*` methods on `dyn PartialReflect` since they are
stop
gaps](https://github.com/bevyengine/bevy/pull/7207#discussion_r1083476050).
- Investigate usages like `ReflectComponent`. In the places they
currently use `PartialReflect`, should they be changed to use `Reflect`?
- Merging this opens the door to lots of reflection features we haven't
been able to implement.
- We could re-add [the `Reflectable`
trait](8e3488c880/crates/bevy_reflect/src/reflect.rs (L337-L342))
and make `FromReflect` a requirement to improve [`FromReflect`
ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is
currently not possible because dynamic types cannot sensibly be
`FromReflect`.
  - Since this is an alternative to #5772, #5781 would be made cleaner.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-08-12 17:01:41 +00:00
Gino Valente
297c0a3954
bevy_reflect: Add DynamicSet to dynamic_types example (#14665)
# Objective

The `dynamic_types` example was missing a reference to the newly added
`DynamicSet` type.

## Solution

Add `DynamicSet` to the `dynamic_types` example.

For parity with the other dynamic types, I also implemented
`FromIterator<T: Reflect>`, `FromIterator<Box<dyn Reflect>>`, and
`IntoIterator for &DynamicSet`.

## Testing

You can run the example locally:

```
cargo run --example dynamic_types
```
2024-08-08 22:26:18 +00:00
Gino Valente
a0cc636ea3
bevy_reflect: Anonymous function parsing (#14641)
# Objective

### TL;DR

#14098 added the `FunctionRegistry` but had some last minute
complications due to anonymous functions. It ended up going with a
"required name" approach to ensure anonymous functions would always have
a name.

However, this approach isn't ideal for named functions since, by
definition, they will always have a name.

Therefore, this PR aims to modify function reflection such that we can
make function registration easier for named functions, while still
allowing anonymous functions to be registered as well.

### Context

Function registration (#14098) ran into a little problem: anonymous
functions.

Anonymous functions, including function pointers, have very non-unique
type names. For example, the anonymous function `|a: i32, b: i32| a + b`
has the type name of `fn(i32, i32) -> i32`. This obviously means we'd
conflict with another function like `|a: i32, b: i32| a - b`.

The solution that #14098 landed on was to always require a name during
function registration.

The downside with this is that named functions (e.g. `fn add(a: i32, b:
i32) -> i32 { a + b }`) had to redundantly provide a name. Additionally,
manually constructed `DynamicFunction`s also ran into this ergonomics
issue.

I don't entirely know how the function registry will be used, but I have
a strong suspicion that most of its registrations will either be named
functions or manually constructed `DynamicFunction`s, with anonymous
functions only being used here and there for quick prototyping or adding
small functionality.

Why then should the API prioritize the anonymous function use case by
always requiring a name during registration?

#### Telling Functions Apart

Rust doesn't provide a lot of out-of-the-box tools for reflecting
functions. One of the biggest hurdles in attempting to solve the problem
outlined above would be to somehow tell the different kinds of functions
apart.

Let's briefly recap on the categories of functions in Rust:

| Category           | Example                                   |
| ------------------ | ----------------------------------------- |
| Named function     | `fn add(a: i32, b: i32) -> i32 { a + b }` |
| Closure            | `\|a: i32\| a + captured_variable`          |
| Anonymous function | `\|a: i32, b: i32\| a + b`                  |
| Function pointer   | `fn(i32, i32) -> i32`                     |

My first thought was to try and differentiate these categories based on
their size. However, we can see that this doesn't quite work:

| Category           | `size_of` |
| ------------------ | --------- |
| Named function     | 0         |
| Closure            | 0+        |
| Anonymous function | 0         |
| Function pointer   | 8         |

Not only does this not tell anonymous functions from named ones, but it
struggles with pretty much all of them.

My second then was to differentiate based on type name:

| Category           | `type_name`             |
| ------------------ | ----------------------- |
| Named function     | `foo::bar::baz`         |
| Closure            | `foo::bar::{{closure}}` |
| Anonymous function | `fn() -> String`        |
| Function pointer   | `fn() -> String`        |

This is much better. While it can't distinguish between function
pointers and anonymous functions, this doesn't matter too much since we
only care about whether we can _name_ the function.

So why didn't we implement this in #14098?

#### Relying on `type_name`

While this solution was known about while working on #14098, it was left
out from that PR due to it being potentially controversial.

The [docs](https://doc.rust-lang.org/stable/std/any/fn.type_name.html)
for `std::any::type_name` state:

> The returned string must not be considered to be a unique identifier
of a type as multiple types may map to the same type name. Similarly,
there is no guarantee that all parts of a type will appear in the
returned string: for example, lifetime specifiers are currently not
included. In addition, the output may change between versions of the
compiler.

So that's it then? We can't use `type_name`?

Well, this statement isn't so much a rule as it is a guideline. And Bevy
is no stranger to bending the rules to make things work or to improve
ergonomics. Remember that before `TypePath`, Bevy's scene system was
entirely dependent on `type_name`. Not to mention that `type_name` is
being used as a key into both the `TypeRegistry` and the
`FunctionRegistry`.

Bevy's practices aside, can we reliably use `type_name` for this?

My answer would be "yes".

Anonymous functions are anonymous. They have no name. There's nothing
Rust could do to give them a name apart from generating a random string
of characters. But remember that this is a diagnostic tool, it doesn't
make sense to obfuscate the type by randomizing the output. So changing
it to be anything other than what it is now is very unlikely.

The only changes that I could potentially see happening are:

1. Closures replace `{{closure}}` with the name of their variable
2. Lifetimes are included in the output

I don't think the first is likely to happen, but if it does then it
actually works out in our favor: closures are now named!

The second point is probably the likeliest. However, adding lifetimes
doesn't mean we can't still rely on `type_name` to determine whether or
not a function is named. So we should be okay in this case as well.

## Solution

Parse the `type_name` of the function in the `TypedFunction` impl to
determine if the function is named or anonymous.

This once again makes `FunctionInfo::name` optional. For manual
constructions of `DynamicFunction`, `FunctionInfo::named` or
``FunctionInfo::anonymous` can be used.

The `FunctionRegistry` API has also been reworked to account for this
change.

`FunctionRegistry::register` no longer takes a name and instead takes it
from the supplied function, returning a
`FunctionRegistrationError::MissingName` error if the name is `None`.
This also doubles as a replacement for the old
`FunctionRegistry::register_dynamic` method, which has been removed.

To handle anonymous functions, a `FunctionRegistry::register_with_name`
method has been added. This works in the same way
`FunctionRegistry::register` used to work before this PR.

The overwriting methods have been updated in a similar manner, with
modifications to `FunctionRegistry::overwrite_registration`, the removal
of `FunctionRegistry::overwrite_registration_dynamic`, and the addition
of `FunctionRegistry::overwrite_registration_with_name`.

This PR also updates the methods on `App` in a similar way:
`App::register_function` no longer requires a name argument and
`App::register_function_with_name` has been added to handle anonymous
functions (and eventually closures).

## Testing

You can run the tests locally by running:

```
cargo test --package bevy_reflect --features functions
```

---

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

> [!note]
> This list is not exhaustive. It only contains some of the most
important changes.

`FunctionRegistry::register` no longer requires a name string for named
functions. Anonymous functions, however, need to be registered using
`FunctionRegistry::register_with_name`.

```rust
// BEFORE
registry
  .register(std::any::type_name_of_val(&foo), foo)?
  .register("bar", || println!("Hello world!"));

// AFTER
registry
  .register(foo)?
  .register_with_name("bar", || println!("Hello world!"));
```

`FunctionInfo::name` is now optional. Anonymous functions and closures
will now have their name set to `None` by default. Additionally,
`FunctionInfo::new` has been renamed to `FunctionInfo::named`.
2024-08-07 03:11:08 +00:00
Gino Valente
df61117850
bevy_reflect: Function registry (#14098)
# Objective

#13152 added support for reflecting functions. Now, we need a way to
register those functions such that they may be accessed anywhere within
the ECS.

## Solution

Added a `FunctionRegistry` type similar to `TypeRegistry`.

This allows a function to be registered and retrieved by name.

```rust
fn foo() -> i32 {
    123
}

let mut registry = FunctionRegistry::default();
registry.register("my_function", foo);

let function = registry.get_mut("my_function").unwrap();
let value = function.call(ArgList::new()).unwrap().unwrap_owned();
assert_eq!(value.downcast_ref::<i32>(), Some(&123));
```

Additionally, I added an `AppFunctionRegistry` resource which wraps a
`FunctionRegistryArc`. Functions can be registered into this resource
using `App::register_function` or by getting a mutable reference to the
resource itself.

### Limitations

#### `Send + Sync`

In order to get this registry to work across threads, it needs to be
`Send + Sync`. This means that `DynamicFunction` needs to be `Send +
Sync`, which means that its internal function also needs to be `Send +
Sync`.

In most cases, this won't be an issue because standard Rust functions
(the type most likely to be registered) are always `Send + Sync`.
Additionally, closures tend to be `Send + Sync` as well, granted they
don't capture any `!Send` or `!Sync` variables.

This PR adds this `Send + Sync` requirement, but as mentioned above, it
hopefully shouldn't be too big of an issue.

#### Closures

Unfortunately, closures can't be registered yet. This will likely be
explored and added in a followup PR.

### Future Work

Besides addressing the limitations listed above, another thing we could
look into is improving the lookup of registered functions. One aspect is
in the performance of hashing strings. The other is in the developer
experience of having to call `std::any::type_name_of_val` to get the
name of their function (assuming they didn't give it a custom name).

## Testing

You can run the tests locally with:

```
cargo test --package bevy_reflect
```

---

## Changelog

- Added `FunctionRegistry`
- Added `AppFunctionRegistry` (a `Resource` available from `bevy_ecs`)
- Added `FunctionRegistryArc`
- Added `FunctionRegistrationError`
- Added `reflect_functions` feature to `bevy_ecs` and `bevy_app`
- `FunctionInfo` is no longer `Default`
- `DynamicFunction` now requires its wrapped function be `Send + Sync`

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

`DynamicFunction` (both those created manually and those created with
`IntoFunction`), now require `Send + Sync`. All standard Rust functions
should meet that requirement. Closures, on the other hand, may not if
they capture any `!Send` or `!Sync` variables from its environment.
2024-08-06 01:09:48 +00:00
Rich Churcher
924f1cbc02
Fix lints in nightly (#14543)
# Objective

Similar to #14537 , this fixes a minor lint issue causing CI failures
when using nightly toolchain.

## Solution

Add `#[allow(dead_code)]` to unused sample code.

## Testing

`cargo run -p ci -- lints` using 1.82 toolchain.
2024-07-31 01:35:19 +00:00
Robert Walter
52a2a3b146
Dedicated Reflect implementation for Set-like things (#13014)
# Objective

I just wanted to inspect `HashSet`s in `bevy-inspector-egui` but I
noticed that it didn't work for some reason. A few minutes later I found
myself looking into the bevy reflect impls noticing that `HashSet`s have
been covered only rudimentary up until now.

## Solution

I'm not sure if this is overkill (especially the first bullet), but
here's a list of the changes:

- created a whole new trait and enum variants for `ReflectRef` and the
like called `Set`
- mostly oriented myself at the `Map` trait and made the necessary
changes until RA was happy
- create macro `impl_reflect_for_hashset!` and call it on `std::HashSet`
and `hashbrown::HashSet`

Extra notes:

- no `get_mut` or `get_mut_at` mirroring the `std::HashSet`
- `insert[_boxed]` and `remove` return `bool` mirroring `std::HashSet`,
additionally that bool is reflect as I thought that would be how we
handle things in bevy reflect, but I'm not sure on this
- ser/de are handled via `SeqAccess`
- I'm not sure about the general deduplication property of this impl of
`Set` that is generally expected? I'm also not sure yet if `Map` does
provide this. This mainly refers to the `Dynamic[...]` structs
- I'm not sure if there are other methods missing from the `trait`, I
felt like `contains` or the set-operations (union/diff/...) could've
been helpful, but I wanted to get out the bare minimum for feedback
first

---

## Changelog

### Added
- `Set` trait for `bevy_reflect`

### Changed
- `std::collections::HashSet` and `bevy_utils::hashbrown::HashSet` now
implement a more complete set of reflect functionalities instead of
"just" `reflect_value`
- `TypeInfo` contains a new variant `Set` that contains `SetInfo`
- `ReflectKind` contains a new variant `Set`
- `ReflectRef` contains a new variant `Set`
- `ReflectMut` contains a new variant `Set`
- `ReflectOwned` contains a new variant `Set`

## Migration Guide

- The new `Set` variants on the enums listed in the change section
should probably be considered by people working with this level of the
lib
### Help wanted! 

I'm not sure if this change is able to break code. From my understanding
it shouldn't since we just add functionality but I'm not sure yet if
theres anything missing from my impl that would be normally provided by
`impl_reflect_value!`
2024-07-24 19:43:26 +00:00
Gino Valente
af865e76a3
bevy_reflect: Improve DynamicFunction ergonomics (#14201)
# Objective

Many functions can be converted to `DynamicFunction` using
`IntoFunction`. Unfortunately, we are limited by Rust itself and the
implementations are far from exhaustive. For example, we can't convert
functions with more than 16 arguments. Additionally, we can't handle
returns with lifetimes not tied to the lifetime of the first argument.

In such cases, users will have to create their `DynamicFunction`
manually.

Let's take the following function:

```rust
fn get(index: usize, list: &Vec<String>) -> &String {
    &list[index]
}
```

This function cannot be converted to a `DynamicFunction` via
`IntoFunction` due to the lifetime of the return value being tied to the
second argument. Therefore, we need to construct the `DynamicFunction`
manually:

```rust
DynamicFunction::new(
    |mut args, info| {
        let list = args
            .pop()
            .unwrap()
            .take_ref::<Vec<String>>(&info.args()[1])?;
        let index = args.pop().unwrap().take_owned::<usize>(&info.args()[0])?;
        Ok(Return::Ref(get(index, list)))
    },
    FunctionInfo::new()
        .with_name("get")
        .with_args(vec![
            ArgInfo:🆕:<usize>(0).with_name("index"),
            ArgInfo:🆕:<&Vec<String>>(1).with_name("list"),
        ])
        .with_return_info(ReturnInfo:🆕:<&String>()),
);
```

While still a small and straightforward snippet, there's a decent amount
going on here. There's a lot of room for improvements when it comes to
ergonomics and readability.

The goal of this PR is to address those issues.

## Solution

Improve the ergonomics and readability of manually created
`DynamicFunction`s.

Some of the major changes:
1. Removed the need for `&ArgInfo` when reifying arguments (i.e. the
`&info.args()[1]` calls)
2. Added additional `pop` methods on `ArgList` to handle both popping
and casting
3. Added `take` methods on `ArgList` for taking the arguments out in
order
4. Removed the need for `&FunctionInfo` in the internal closure (Change
1 made it no longer necessary)
5. Added methods to automatically handle generating `ArgInfo` and
`ReturnInfo`

With all these changes in place, we get something a lot nicer to both
write and look at:

```rust
DynamicFunction::new(
    |mut args| {
        let index = args.take::<usize>()?;
        let list = args.take::<&Vec<String>>()?;
        Ok(Return::Ref(get(index, list)))
    },
    FunctionInfo::new()
        .with_name("get")
        .with_arg::<usize>("index")
        .with_arg::<&Vec<String>>("list")
        .with_return::<&String>(),
);
```

Alternatively, to rely on type inference for taking arguments, you could
do:

```rust
DynamicFunction::new(
    |mut args| {
        let index = args.take_owned()?;
        let list = args.take_ref()?;
        Ok(Return::Ref(get(index, list)))
    },
    FunctionInfo::new()
        .with_name("get")
        .with_arg::<usize>("index")
        .with_arg::<&Vec<String>>("list")
        .with_return::<&String>(),
);
```

## Testing

You can test locally by running:

```
cargo test --package bevy_reflect
```

---

## Changelog

- Removed `&ArgInfo` argument from `FromArg::from_arg` trait method
- Removed `&ArgInfo` argument from `Arg::take_***` methods
- Added `ArgValue`
- `Arg` is now a struct containing an `ArgValue` and an argument `index`
- `Arg::take_***` methods now require `T` is also `TypePath`
- Added `Arg::new`, `Arg::index`, `Arg::value`, `Arg::take_value`, and
`Arg::take` methods
- Replaced `ArgId` in `ArgError` with just the argument `index`
- Added `ArgError::EmptyArgList`
- Renamed `ArgList::push` to `ArgList::push_arg`
- Added `ArgList::pop_arg`, `ArgList::pop_owned`, `ArgList::pop_ref`,
and `ArgList::pop_mut`
- Added `ArgList::take_arg`, `ArgList::take_owned`, `ArgList::take_ref`,
`ArgList::take_mut`, and `ArgList::take`
- `ArgList::pop` is now generic
- Renamed `FunctionError::InvalidArgCount` to
`FunctionError::ArgCountMismatch`
- The closure given to `DynamicFunction::new` no longer has a
`&FunctionInfo` argument
- Added `FunctionInfo::with_arg`
- Added `FunctionInfo::with_return`

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

* The `FromArg::from_arg` trait method and the `Arg::take_***` methods
no longer take a `&ArgInfo` argument.
* What used to be `Arg` is now `ArgValue`. `Arg` is now a struct which
contains an `ArgValue`.
* `Arg::take_***` methods now require `T` is also `TypePath`
* Instances of `id: ArgId` in `ArgError` have been replaced with `index:
usize`
* `ArgList::push` is now `ArgList::push_arg`. It also takes the new
`ArgValue` type.
* `ArgList::pop` has become `ArgList::pop_arg` and now returns
`ArgValue`. `Arg::pop` now takes a generic type and downcasts to that
type. It's recommended to use `ArgList::take` and friends instead since
they allow removing the arguments from the list in the order they were
pushed (rather than reverse order).
* `FunctionError::InvalidArgCount` is now
`FunctionError::ArgCountMismatch`
* The closure given to `DynamicFunction::new` no longer has a
`&FunctionInfo` argument. This argument can be removed.
2024-07-16 13:01:52 +00:00
Gino Valente
1042f09c2e
bevy_reflect: Add DynamicClosure and DynamicClosureMut (#14141)
# Objective

As mentioned in
[this](https://github.com/bevyengine/bevy/pull/13152#issuecomment-2198387297)
comment, creating a function registry (see #14098) is a bit difficult
due to the requirements of `DynamicFunction`. Internally, a
`DynamicFunction` contains a `Box<dyn FnMut>` (the function that reifies
reflected arguments and calls the actual function), which requires `&mut
self` in order to be called.

This means that users would require a mutable reference to the function
registry for it to be useful— which isn't great. And they can't clone
the `DynamicFunction` either because cloning an `FnMut` isn't really
feasible (wrapping it in an `Arc` would allow it to be cloned but we
wouldn't be able to call the clone since we need a mutable reference to
the `FnMut`, which we can't get with multiple `Arc`s still alive,
requiring us to also slap in a `Mutex`, which adds additional overhead).

And we don't want to just replace the `dyn FnMut` with `dyn Fn` as that
would prevent reflecting closures that mutate their environment.

Instead, we need to introduce a new type to split the requirements of
`DynamicFunction`.

## Solution

Introduce new types for representing closures.

Specifically, this PR introduces `DynamicClosure` and
`DynamicClosureMut`. Similar to how `IntoFunction` exists for
`DynamicFunction`, two new traits were introduced: `IntoClosure` and
`IntoClosureMut`.

Now `DynamicFunction` stores a `dyn Fn` with a `'static` lifetime.
`DynamicClosure` also uses a `dyn Fn` but has a lifetime, `'env`, tied
to its environment. `DynamicClosureMut` is most like the old
`DynamicFunction`, keeping the `dyn FnMut` and also typing its lifetime,
`'env`, to the environment

Here are some comparison tables:

|   | `DynamicFunction` | `DynamicClosure` | `DynamicClosureMut` |
| - | ----------------- | ---------------- | ------------------- |
| Callable with `&self` |  |  |  |
| Callable with `&mut self` |  |  |  |
| Allows for non-`'static` lifetimes |  |  |  |

|   | `IntoFunction` | `IntoClosure` | `IntoClosureMut` |
| - | -------------- | ------------- | ---------------- |
| Convert `fn` functions |  |  |  |
| Convert `fn` methods |  |  |  |
| Convert anonymous functions |  |  |  |
| Convert closures that capture immutable references |  |  |  |
| Convert closures that capture mutable references |  |  |  |
| Convert closures that capture owned values | [^1] |  |  |

[^1]: Due to limitations in Rust, `IntoFunction` can't be implemented
for just functions (unless we forced users to manually coerce them to
function pointers first). So closures that meet the trait requirements
_can technically_ be converted into a `DynamicFunction` as well. To both
future-proof and reduce confusion, though, we'll just pretend like this
isn't a thing.

```rust
let mut list: Vec<i32> = vec![1, 2, 3];

// `replace` is a closure that captures a mutable reference to `list`
let mut replace = |index: usize, value: i32| -> i32 {
  let old_value = list[index];
  list[index] = value;
  old_value
};

// Convert the closure into a dynamic closure using `IntoClosureMut::into_closure_mut`
let mut func: DynamicClosureMut = replace.into_closure_mut();

// Dynamically call the closure:
let args = ArgList::default().push_owned(1_usize).push_owned(-2_i32);
let value = func.call_once(args).unwrap().unwrap_owned();

// Check the result:
assert_eq!(value.take::<i32>().unwrap(), 2);
assert_eq!(list, vec![1, -2, 3]);
```

### `ReflectFn`/`ReflectFnMut`

To make extending the function reflection system easier (the blanket
impls for `IntoFunction`, `IntoClosure`, and `IntoClosureMut` are all
incredibly short), this PR generalizes callables with two new traits:
`ReflectFn` and `ReflectFnMut`.

These traits mimic `Fn` and `FnMut` but allow for being called via
reflection. In fact, their blanket implementations are identical save
for `ReflectFn` being implemented over `Fn` types and `ReflectFnMut`
being implemented over `FnMut` types.

And just as `Fn` is a subtrait of `FnMut`, `ReflectFn` is a subtrait of
`ReflectFnMut`. So anywhere that expects a `ReflectFnMut` can also be
given a `ReflectFn`.

To reiterate, these traits aren't 100% necessary. They were added in
purely for extensibility. If we decide to split things up differently or
add new traits/types in the future, then those changes should be much
simpler to implement.

### `TypedFunction`

Because of the split into `ReflectFn` and `ReflectFnMut`, we needed a
new way to access the function type information. This PR moves that
concept over into `TypedFunction`.

Much like `Typed`, this provides a way to access a function's
`FunctionInfo`.

By splitting this trait out, it helps to ensure the other traits are
focused on a single responsibility.

### Internal Macros

The original function PR (#13152) implemented `IntoFunction` using a
macro which was passed into an `all_tuples!` macro invocation. Because
we needed the same functionality for these new traits, this PR has
copy+pasted that code for `ReflectFn`, `ReflectFnMut`, and
`TypedFunction`— albeit with some differences between them.

Originally, I was going to try and macro-ify the impls and where clauses
such that we wouldn't have to straight up duplicate a lot of this logic.
However, aside from being more complex in general, autocomplete just
does not play nice with such heavily nested macros (tried in both
RustRover and VSCode). And both of those problems told me that it just
wasn't worth it: we need to ensure the crate is easily maintainable,
even at the cost of duplicating code.

So instead, I made sure to simplify the macro code by removing all
fully-qualified syntax and cutting the where clauses down to the bare
essentials, which helps to clean up a lot of the visual noise. I also
tried my best to document the macro logic in certain areas (I may even
add a bit more) to help with maintainability for future devs.

### Documentation

Documentation for this module was a bit difficult for me. So many of
these traits and types are very interconnected. And each trait/type has
subtle differences that make documenting it in a single place, like at
the module level, difficult to do cleanly. Describing the valid
signatures is also challenging to do well.

Hopefully what I have here is okay. I think I did an okay job, but let
me know if there any thoughts on ways to improve it. We can also move
such a task to a followup PR for more focused discussion.

## Testing

You can test locally by running:

```
cargo test --package bevy_reflect
```

---

## Changelog

- Added `DynamicClosure` struct
- Added `DynamicClosureMut` struct
- Added `IntoClosure` trait
- Added `IntoClosureMut` trait
- Added `ReflectFn` trait
- Added `ReflectFnMut` trait
- Added `TypedFunction` trait
- `IntoFunction` now only works for standard Rust functions
- `IntoFunction` no longer takes a lifetime parameter
- `DynamicFunction::call` now only requires `&self`
- Removed `DynamicFunction::call_once`
- Changed the `IntoReturn::into_return` signature to include a where
clause

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

### `IntoClosure`

`IntoFunction` now only works for standard Rust functions. Calling
`IntoFunction::into_function` on a closure that captures references to
its environment (either mutable or immutable), will no longer compile.

Instead, you will need to use either `IntoClosure::into_closure` to
create a `DynamicClosure` or `IntoClosureMut::into_closure_mut` to
create a `DynamicClosureMut`, depending on your needs:

```rust
let punct = String::from("!");
let print = |value: String| {
    println!("{value}{punct}");
};

// BEFORE
let func: DynamicFunction = print.into_function();

// AFTER
let func: DynamicClosure = print.into_closure();
```

### `IntoFunction` lifetime

Additionally, `IntoFunction` no longer takes a lifetime parameter as it
always expects a `'static` lifetime. Usages will need to remove any
lifetime parameters:

```rust
// BEFORE
fn execute<'env, F: IntoFunction<'env, Marker>, Marker>(f: F) {/* ... */}

// AFTER
fn execute<F: IntoFunction<Marker>, Marker>(f: F) {/* ... */}
```

### `IntoReturn`

`IntoReturn::into_return` now has a where clause. Any manual
implementors will need to add this where clause to their implementation.
2024-07-16 03:22:43 +00:00
SpecificProtagonist
ab255aefc6
Implement FromIterator/IntoIterator for dynamic types (#14250)
# Objective

Implement FromIterator/IntoIterator for dynamic types where missing

Note:
- can't impl `IntoIterator` for `&Array` & co because of orphan rules
- `into_iter().collect()` is a no-op for `Vec`s because of
specialization

---

## Migration Guide

- Change `DynamicArray::from_vec` to `DynamicArray::from_iter`
2024-07-15 15:38:11 +00:00
Gino Valente
276815a9a0
examples: Add Type Data reflection example (#13903)
# Objective

Type data is a **super** useful tool to know about when working with
reflection. However, most users don't fully understand how it works or
that you can use it for more than just object-safe traits.

This is unfortunate because it can be surprisingly simple to manually
create your own type data.

We should have an example detailing how type works, how users can define
their own, and how thy can be used.

## Solution

Added a `type_data` example.

This example goes through all the major points about type data:
- Why we need them
- How they can be defined
- The two ways they can be registered
- A list of common/important type data provided by Bevy

I also thought it might be good to go over the `#[reflect_trait]` macro
as part of this example since it has all the other context, including
how to define type data in places where `#[reflect_trait]` won't work.
Because of this, I removed the `trait_reflection` example.

## Testing

You can run the example locally with the following command:

```
cargo run --example type_data
```

---

## Changelog

- Added the `type_data` example
- Removed the `trait_reflection` example
2024-07-15 14:19:50 +00:00
Gino Valente
276dd04001
bevy_reflect: Function reflection (#13152)
# Objective

We're able to reflect types sooooooo... why not functions?

The goal of this PR is to make functions callable within a dynamic
context, where type information is not readily available at compile
time.

For example, if we have a function:

```rust
fn add(left: i32, right: i32) -> i32 {
  left + right
}
```

And two `Reflect` values we've already validated are `i32` types:

```rust
let left: Box<dyn Reflect> = Box::new(2_i32);
let right: Box<dyn Reflect> = Box::new(2_i32);
```

We should be able to call `add` with these values:

```rust
// ?????
let result: Box<dyn Reflect> = add.call_dynamic(left, right);
```

And ideally this wouldn't just work for functions, but methods and
closures too!

Right now, users have two options:

1. Manually parse the reflected data and call the function themselves
2. Rely on registered type data to handle the conversions for them

For a small function like `add`, this isn't too bad. But what about for
more complex functions? What about for many functions?

At worst, this process is error-prone. At best, it's simply tedious.

And this is assuming we know the function at compile time. What if we
want to accept a function dynamically and call it with our own
arguments?

It would be much nicer if `bevy_reflect` could alleviate some of the
problems here.

## Solution

Added function reflection!

This adds a `DynamicFunction` type to wrap a function dynamically. This
can be called with an `ArgList`, which is a dynamic list of
`Reflect`-containing `Arg` arguments. It returns a `FunctionResult`
which indicates whether or not the function call succeeded, returning a
`Reflect`-containing `Return` type if it did succeed.

Many functions can be converted into this `DynamicFunction` type thanks
to the `IntoFunction` trait.

Taking our previous `add` example, this might look something like
(explicit types added for readability):

```rust
fn add(left: i32, right: i32) -> i32 {
  left + right
}

let mut function: DynamicFunction = add.into_function();
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
let result: Return = function.call(args).unwrap();
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

And it also works on closures:

```rust
let add = |left: i32, right: i32| left + right;

let mut function: DynamicFunction = add.into_function();
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
let result: Return = function.call(args).unwrap();
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

As well as methods:

```rust
#[derive(Reflect)]
struct Foo(i32);

impl Foo {
  fn add(&mut self, value: i32) {
    self.0 += value;
  }
}

let mut foo = Foo(2);

let mut function: DynamicFunction = Foo::add.into_function();
let args: ArgList = ArgList::new().push_mut(&mut foo).push_owned(2_i32);
function.call(args).unwrap();
assert_eq!(foo.0, 4);
```

### Limitations

While this does cover many functions, it is far from a perfect system
and has quite a few limitations. Here are a few of the limitations when
using `IntoFunction`:

1. The lifetime of the return value is only tied to the lifetime of the
first argument (useful for methods). This means you can't have a
function like `(a: i32, b: &i32) -> &i32` without creating the
`DynamicFunction` manually.
2. Only 15 arguments are currently supported. If the first argument is a
(mutable) reference, this number increases to 16.
3. Manual implementations of `Reflect` will need to implement the new
`FromArg`, `GetOwnership`, and `IntoReturn` traits in order to be used
as arguments/return types.

And some limitations of `DynamicFunction` itself:

1. All arguments share the same lifetime, or rather, they will shrink to
the shortest lifetime.
2. Closures that capture their environment may need to have their
`DynamicFunction` dropped before accessing those variables again (there
is a `DynamicFunction::call_once` to make this a bit easier)
3. All arguments and return types must implement `Reflect`. While not a
big surprise coming from `bevy_reflect`, this implementation could
actually still work by swapping `Reflect` out with `Any`. Of course,
that makes working with the arguments and return values a bit harder.
4. Generic functions are not supported (unless they have been manually
monomorphized)

And general, reflection gotchas:

1. `&str` does not implement `Reflect`. Rather, `&'static str`
implements `Reflect` (the same is true for `&Path` and similar types).
This means that `&'static str` is considered an "owned" value for the
sake of generating arguments. Additionally, arguments and return types
containing `&str` will assume it's `&'static str`, which is almost never
the desired behavior. In these cases, the only solution (I believe) is
to use `&String` instead.

### Followup Work

This PR is the first of two PRs I intend to work on. The second PR will
aim to integrate this new function reflection system into the existing
reflection traits and `TypeInfo`. The goal would be to register and call
a reflected type's methods dynamically.

I chose not to do that in this PR since the diff is already quite large.
I also want the discussion for both PRs to be focused on their own
implementation.

Another followup I'd like to do is investigate allowing common container
types as a return type, such as `Option<&[mut] T>` and `Result<&[mut] T,
E>`. This would allow even more functions to opt into this system. I
chose to not include it in this one, though, for the same reasoning as
previously mentioned.

### Alternatives

One alternative I had considered was adding a macro to convert any
function into a reflection-based counterpart. The idea would be that a
struct that wraps the function would be created and users could specify
which arguments and return values should be `Reflect`. It could then be
called via a new `Function` trait.

I think that could still work, but it will be a fair bit more involved,
requiring some slightly more complex parsing. And it of course is a bit
more work for the user, since they need to create the type via macro
invocation.

It also makes registering these functions onto a type a bit more
complicated (depending on how it's implemented).

For now, I think this is a fairly simple, yet powerful solution that
provides the least amount of friction for users.

---

## Showcase

Bevy now adds support for storing and calling functions dynamically
using reflection!

```rust
// 1. Take a standard Rust function
fn add(left: i32, right: i32) -> i32 {
  left + right
}

// 2. Convert it into a type-erased `DynamicFunction` using the `IntoFunction` trait
let mut function: DynamicFunction = add.into_function();
// 3. Define your arguments from reflected values
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
// 4. Call the function with your arguments
let result: Return = function.call(args).unwrap();
// 5. Extract the return value
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

## Changelog

#### TL;DR

- Added support for function reflection
- Added a new `Function Reflection` example:
ba727898f2/examples/reflection/function_reflection.rs (L1-L157)

#### Details

Added the following items:

- `ArgError` enum
- `ArgId` enum
- `ArgInfo` struct
- `ArgList` struct
- `Arg` enum
- `DynamicFunction` struct
- `FromArg` trait (derived with `derive(Reflect)`)
- `FunctionError` enum
- `FunctionInfo` struct
- `FunctionResult` alias
- `GetOwnership` trait (derived with `derive(Reflect)`)
- `IntoFunction` trait (with blanket implementation)
- `IntoReturn` trait (derived with `derive(Reflect)`)
- `Ownership` enum
- `ReturnInfo` struct
- `Return` enum

---------

Co-authored-by: Periwink <charlesbour@gmail.com>
2024-07-01 13:49:08 +00:00
Gino Valente
5db52663b3
bevy_reflect: Custom attributes (#11659)
# Objective

As work on the editor starts to ramp up, it might be nice to start
allowing types to specify custom attributes. These can be used to
provide certain functionality to fields, such as ranges or controlling
how data is displayed.

A good example of this can be seen in
[`bevy-inspector-egui`](https://github.com/jakobhellermann/bevy-inspector-egui)
with its
[`InspectorOptions`](https://docs.rs/bevy-inspector-egui/0.22.1/bevy_inspector_egui/struct.InspectorOptions.html):

```rust
#[derive(Reflect, Default, InspectorOptions)]
#[reflect(InspectorOptions)]
struct Slider {
    #[inspector(min = 0.0, max = 1.0)]
    value: f32,
}
```

Normally, as demonstrated in the example above, these attributes are
handled by a derive macro and stored in a corresponding `TypeData`
struct (i.e. `ReflectInspectorOptions`).

Ideally, we would have a good way of defining this directly via
reflection so that users don't need to create and manage a whole proc
macro just to allow these sorts of attributes.

And note that this doesn't have to just be for inspectors and editors.
It can be used for things done purely on the code side of things.

## Solution

Create a new method for storing attributes on fields via the `Reflect`
derive.

These custom attributes are stored in type info (e.g. `NamedField`,
`StructInfo`, etc.).

```rust
#[derive(Reflect)]
struct Slider {
    #[reflect(@0.0..=1.0)]
    value: f64,
}

let TypeInfo::Struct(info) = Slider::type_info() else {
    panic!("expected struct info");
};

let field = info.field("value").unwrap();

let range = field.get_attribute::<RangeInclusive<f64>>().unwrap();
assert_eq!(*range, 0.0..=1.0);
```

## TODO

- [x] ~~Bikeshed syntax~~ Went with a type-based approach, prefixed by
`@` for ease of parsing and flexibility
- [x] Add support for custom struct/tuple struct field attributes
- [x] Add support for custom enum variant field attributes
- [x] ~~Add support for custom enum variant attributes (maybe?)~~ ~~Will
require a larger refactor. Can be saved for a future PR if we really
want it.~~ Actually, we apparently still have support for variant
attributes despite not using them, so it was pretty easy to add lol.
- [x] Add support for custom container attributes
- [x] Allow custom attributes to store any reflectable value (not just
`Lit`)
- [x] ~~Store attributes in registry~~ This PR used to store these in
attributes in the registry, however, it has since switched over to
storing them in type info
- [x] Add example

## Bikeshedding

> [!note]
> This section was made for the old method of handling custom
attributes, which stored them by name (i.e. `some_attribute = 123`). The
PR has shifted away from that, to a more type-safe approach.
>
> This section has been left for reference.

There are a number of ways we can syntactically handle custom
attributes. Feel free to leave a comment on your preferred one! Ideally
we want one that is clear, readable, and concise since these will
potentially see _a lot_ of use.

Below is a small, non-exhaustive list of them. Note that the
`skip_serializing` reflection attribute is added to demonstrate how each
case plays with existing reflection attributes.

<details>
<summary>List</summary>

##### 1. `@(name = value)`

> The `@` was chosen to make them stand out from other attributes and
because the "at" symbol is a subtle pneumonic for "attribute". Of
course, other symbols could be used (e.g. `$`, `#`, etc.).

```rust
#[derive(Reflect)]
struct Slider {
    #[reflect(@(min = 0.0, max = 1.0), skip_serializing)]
    #[[reflect(@(bevy_editor::hint = "Range: 0.0 to 1.0"))]
    value: f32,
}
```

##### 2. `@name = value`

> This is my personal favorite.

```rust
#[derive(Reflect)]
struct Slider {
    #[reflect(@min = 0.0, @max = 1.0, skip_serializing)]
    #[[reflect(@bevy_editor::hint = "Range: 0.0 to 1.0")]
    value: f32,
}
```

##### 3. `custom_attr(name = value)`

> `custom_attr` can be anything. Other possibilities include `with` or
`tag`.

```rust
#[derive(Reflect)]
struct Slider {
    #[reflect(custom_attr(min = 0.0, max = 1.0), skip_serializing)]
    #[[reflect(custom_attr(bevy_editor::hint = "Range: 0.0 to 1.0"))]
    value: f32,
}
```

##### 4. `reflect_attr(name = value)`

```rust
#[derive(Reflect)]
struct Slider {
    #[reflect(skip_serializing)]
    #[reflect_attr(min = 0.0, max = 1.0)]
    #[[reflect_attr(bevy_editor::hint = "Range: 0.0 to 1.0")]
    value: f32,
}
```

</details>

---

## Changelog

- Added support for custom attributes on reflected types (i.e.
`#[reflect(@Foo::new("bar")]`)
2024-05-20 19:30:21 +00:00
Gino Valente
40837501b4
examples: Add Dynamic Types reflection example (#13220)
# Objective

Dynamic types can be tricky to understand and work with in bevy_reflect.
There should be an example that shows what they are and how they're
used.

## Solution

Add a `Dynamic Types` reflection example.

I'm planning to go through the reflection examples, adding new ones and
updating old ones. And I think this walkthrough style tends to work
best. Due to the amount of text and associated explanation, it might fit
better in a dedicated reflection chapter of the WIP Bevy Book. However,
I think it might be valuable to have some public-facing tutorials for
these concepts.

Let me know if there any thoughts or critiques with the example— both in
content and this overall structure!

## Testing

To test these changes, you can run the example locally:

```
cargo run --example dynamic_types
```

---

## Changelog

- Add `Dynamic Types` reflection example
2024-05-03 23:34:53 +00:00
Gino Valente
0265436fff
bevy_reflect: Rename UntypedReflectDeserializer to ReflectDeserializer (#12721)
# Objective

We have `ReflectSerializer` and `TypedReflectSerializer`. The former is
the one users will most often use since the latter takes a bit more
effort to deserialize.

However, our deserializers are named `UntypedReflectDeserializer` and
`TypedReflectDeserializer`. There is no obvious indication that
`UntypedReflectDeserializer` must be used with `ReflectSerializer` since
the names don't quite match up.

## Solution

Rename `UntypedReflectDeserializer` back to `ReflectDeserializer`
(initially changed as part of #5723).

Also update the docs for both deserializers (as they were pretty out of
date) and include doc examples.

I also updated the docs for the serializers, too, just so that
everything is consistent.

---

## Changelog

- Renamed `UntypedReflectDeserializer` to `ReflectDeserializer`
- Updated docs for `ReflectDeserializer`, `TypedReflectDeserializer`,
`ReflectSerializer`, and `TypedReflectSerializer`

## Migration Guide

`UntypedReflectDeserializer` has been renamed to `ReflectDeserializer`.
Usages will need to be updated accordingly.

```diff
- let reflect_deserializer = UntypedReflectDeserializer::new(&registry);
+ let reflect_deserializer = ReflectDeserializer::new(&registry);
```
2024-03-26 19:58:29 +00:00
James Liu
9e5db9abc7
Clean up type registrations (#12314)
# Objective
Fix #12304. Remove unnecessary type registrations thanks to #4154.

## Solution
Conservatively remove type registrations. Keeping the top level
components, resources, and events, but dropping everything else that is
a type of a member of those types.
2024-03-06 16:05:53 +00:00
Gino Valente
ccb9d0500f
bevy_reflect: Recursive registration (#5781)
# Objective

Resolves #4154

Currently, registration must all be done manually:

```rust
#[derive(Reflect)]
struct Foo(Bar);

#[derive(Reflect)]
struct Bar(Baz);

#[derive(Reflect)]
struct Baz(usize);

fn main() {
  // ...
  app
    .register_type::<Foo>()
    .register_type::<Bar>()
    .register_type::<Baz>()
    // .register_type::<usize>() <- This one is handled by Bevy, thankfully
  // ...
}
```

This can grow really quickly and become very annoying to add, remove,
and update as types change. It would be great if we could help reduce
the number of types that a user must manually implement themselves.

## Solution

As suggested in #4154, this PR adds automatic recursive registration.
Essentially, when a type is registered, it may now also choose to
register additional types along with it using the new
`GetTypeRegistration::register_type_dependencies` trait method.

The `Reflect` derive macro now automatically does this for all fields in
structs, tuple structs, struct variants, and tuple variants. This is
also done for tuples, arrays, `Vec<T>`, `HashMap<K, V>`, and
`Option<T>`.

This allows us to simplify the code above like:

```rust
#[derive(Reflect)]
struct Foo(Bar);

#[derive(Reflect)]
struct Bar(Baz);

#[derive(Reflect)]
struct Baz(usize);

fn main() {
  // ...
  app.register_type::<Foo>()
  // ...
}
```

This automatic registration only occurs if the type has not yet been
registered. If it has been registered, we simply skip it and move to the
next one. This reduces the cost of registration and prevents overwriting
customized registrations.

## Considerations

While this does improve ergonomics on one front, it's important to look
at some of the arguments against adopting a PR like this.

#### Generic Bounds

~~Since we need to be able to register the fields individually, we need
those fields to implement `GetTypeRegistration`. This forces users to
then add this trait as a bound on their generic arguments. This
annoyance could be relieved with something like #5772.~~

This is no longer a major issue as the `Reflect` derive now adds the
`GetTypeRegistration` bound by default. This should technically be okay,
since we already add the `Reflect` bound.

However, this can also be considered a breaking change for manual
implementations that left out a `GetTypeRegistration` impl ~~or for
items that contain dynamic types (e.g. `DynamicStruct`) since those also
do not implement `GetTypeRegistration`~~.

#### Registration Assumptions

By automatically registering fields, users might inadvertently be
relying on certain types to be automatically registered. If `Foo`
auto-registers `Bar`, but `Foo` is later removed from the code, then
anywhere that previously used or relied on `Bar`'s registration would
now fail.

---

## Changelog

- Added recursive type registration to structs, tuple structs, struct
variants, tuple variants, tuples, arrays, `Vec<T>`, `HashMap<K, V>`, and
`Option<T>`
- Added a new trait in the hidden `bevy_reflect::__macro_exports` module
called `RegisterForReflection`
- Added `GetTypeRegistration` impl for
`bevy_render::render_asset::RenderAssetUsages`

## Migration Guide

All types that derive `Reflect` will now automatically add
`GetTypeRegistration` as a bound on all (unignored) fields. This means
that all reflected fields will need to also implement
`GetTypeRegistration`.

If all fields **derive** `Reflect` or are implemented in `bevy_reflect`,
this should not cause any issues. However, manual implementations of
`Reflect` that excluded a `GetTypeRegistration` impl for their type will
need to add one.

```rust
#[derive(Reflect)]
struct Foo<T: FromReflect> {
  data: MyCustomType<T>
}

// OLD
impl<T: FromReflect> Reflect for MyCustomType<T> {/* ... */}

// NEW
impl<T: FromReflect + GetTypeRegistration> Reflect for MyCustomType<T> {/* ... */}
impl<T: FromReflect + GetTypeRegistration> GetTypeRegistration for MyCustomType<T> {/* ... */}
```

---------

Co-authored-by: James Liu <contact@jamessliu.com>
Co-authored-by: radiish <cb.setho@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-03-04 19:04:10 +00:00
Tristan Guichaoua
694c06f3d0
Inverse missing_docs logic (#11676)
# Objective

Currently the `missing_docs` lint is allowed-by-default and enabled at
crate level when their documentations is complete (see #3492).
This PR proposes to inverse this logic by making `missing_docs`
warn-by-default and mark crates with imcomplete docs allowed.

## Solution

Makes `missing_docs` warn at workspace level and allowed at crate level
when the docs is imcomplete.
2024-02-03 21:40:55 +00:00
radiish
262846e702
reflect: TypePath part 2 (#8768)
# Objective

- Followup to #7184.
- ~Deprecate `TypeUuid` and remove its internal references.~ No longer
part of this PR.
- Use `TypePath` for the type registry, and (de)serialisation instead of
`std::any::type_name`.
- Allow accessing type path information behind proxies.

## Solution
- Introduce methods on `TypeInfo` and friends for dynamically querying
type path. These methods supersede the old `type_name` methods.
- Remove `Reflect::type_name` in favor of `DynamicTypePath::type_path`
and `TypeInfo::type_path_table`.
- Switch all uses of `std::any::type_name` in reflection, non-debugging
contexts to use `TypePath`.

---

## Changelog

- Added `TypePathTable` for dynamically accessing methods on `TypePath`
through `TypeInfo` and the type registry.
- Removed `type_name` from all `TypeInfo`-like structs.
- Added `type_path` and `type_path_table` methods to all `TypeInfo`-like
structs.
- Removed `Reflect::type_name` in favor of
`DynamicTypePath::reflect_type_path` and `TypeInfo::type_path`.
- Changed the signature of all `DynamicTypePath` methods to return
strings with a static lifetime.

## Migration Guide

- Rely on `TypePath` instead of `std::any::type_name` for all stability
guarantees and for use in all reflection contexts, this is used through
with one of the following APIs:
  - `TypePath::type_path` if you have a concrete type and not a value.
- `DynamicTypePath::reflect_type_path` if you have an `dyn Reflect`
value without a concrete type.
- `TypeInfo::type_path` for use through the registry or if you want to
work with the represented type of a `DynamicFoo`.
  
- Remove `type_name` from manual `Reflect` implementations.
- Use `type_path` and `type_path_table` in place of `type_name` on
`TypeInfo`-like structs.
- Use `get_with_type_path(_mut)` over `get_with_type_name(_mut)`.

## Note to reviewers

I think if anything we were a little overzealous in merging #7184 and we
should take that extra care here.

In my mind, this is the "point of no return" for `TypePath` and while I
think we all agree on the design, we should carefully consider if the
finer details and current implementations are actually how we want them
moving forward.

For example [this incorrect `TypePath` implementation for
`String`](3fea3c6c0b/crates/bevy_reflect/src/impls/std.rs (L90))
(note that `String` is in the default Rust prelude) snuck in completely
under the radar.
2023-10-09 19:33:03 +00:00
Gino Valente
aeeb20ec4c
bevy_reflect: FromReflect Ergonomics Implementation (#6056)
# Objective

**This implementation is based on
https://github.com/bevyengine/rfcs/pull/59.**

---

Resolves #4597

Full details and motivation can be found in the RFC, but here's a brief
summary.

`FromReflect` is a very powerful and important trait within the
reflection API. It allows Dynamic types (e.g., `DynamicList`, etc.) to
be formed into Real ones (e.g., `Vec<i32>`, etc.).

This mainly comes into play concerning deserialization, where the
reflection deserializers both return a `Box<dyn Reflect>` that almost
always contain one of these Dynamic representations of a Real type. To
convert this to our Real type, we need to use `FromReflect`.

It also sneaks up in other ways. For example, it's a required bound for
`T` in `Vec<T>` so that `Vec<T>` as a whole can be made `FromReflect`.
It's also required by all fields of an enum as it's used as part of the
`Reflect::apply` implementation.

So in other words, much like `GetTypeRegistration` and `Typed`, it is
very much a core reflection trait.

The problem is that it is not currently treated like a core trait and is
not automatically derived alongside `Reflect`. This makes using it a bit
cumbersome and easy to forget.

## Solution

Automatically derive `FromReflect` when deriving `Reflect`.

Users can then choose to opt-out if needed using the
`#[reflect(from_reflect = false)]` attribute.

```rust
#[derive(Reflect)]
struct Foo;

#[derive(Reflect)]
#[reflect(from_reflect = false)]
struct Bar;

fn test<T: FromReflect>(value: T) {}

test(Foo); // <-- OK
test(Bar); // <-- Panic! Bar does not implement trait `FromReflect`
```

#### `ReflectFromReflect`

This PR also automatically adds the `ReflectFromReflect` (introduced in
#6245) registration to the derived `GetTypeRegistration` impl— if the
type hasn't opted out of `FromReflect` of course.

<details>
<summary><h4>Improved Deserialization</h4></summary>

> **Warning**
> This section includes changes that have since been descoped from this
PR. They will likely be implemented again in a followup PR. I am mainly
leaving these details in for archival purposes, as well as for reference
when implementing this logic again.

And since we can do all the above, we might as well improve
deserialization. We can now choose to deserialize into a Dynamic type or
automatically convert it using `FromReflect` under the hood.

`[Un]TypedReflectDeserializer::new` will now perform the conversion and
return the `Box`'d Real type.

`[Un]TypedReflectDeserializer::new_dynamic` will work like what we have
now and simply return the `Box`'d Dynamic type.

```rust
// Returns the Real type
let reflect_deserializer = UntypedReflectDeserializer::new(&registry);
let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;

let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?;

// Returns the Dynamic type
let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry);
let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;

let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?;
```

</details>

---

## Changelog

* `FromReflect` is now automatically derived within the `Reflect` derive
macro
* This includes auto-registering `ReflectFromReflect` in the derived
`GetTypeRegistration` impl
* ~~Renamed `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` to
`TypedReflectDeserializer::new_dynamic` and
`UntypedReflectDeserializer::new_dynamic`, respectively~~ **Descoped**
* ~~Changed `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` to automatically convert the
deserialized output using `FromReflect`~~ **Descoped**

## Migration Guide

* `FromReflect` is now automatically derived within the `Reflect` derive
macro. Items with both derives will need to remove the `FromReflect`
one.

  ```rust
  // OLD
  #[derive(Reflect, FromReflect)]
  struct Foo;
  
  // NEW
  #[derive(Reflect)]
  struct Foo;
  ```

If using a manual implementation of `FromReflect` and the `Reflect`
derive, users will need to opt-out of the automatic implementation.

  ```rust
  // OLD
  #[derive(Reflect)]
  struct Foo;
  
  impl FromReflect for Foo {/* ... */}
  
  // NEW
  #[derive(Reflect)]
  #[reflect(from_reflect = false)]
  struct Foo;
  
  impl FromReflect for Foo {/* ... */}
  ```

<details>
<summary><h4>Removed Migrations</h4></summary>

> **Warning**
> This section includes changes that have since been descoped from this
PR. They will likely be implemented again in a followup PR. I am mainly
leaving these details in for archival purposes, as well as for reference
when implementing this logic again.

* The reflect deserializers now perform a `FromReflect` conversion
internally. The expected output of `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` is no longer a Dynamic (e.g.,
`DynamicList`), but its Real counterpart (e.g., `Vec<i32>`).

  ```rust
let reflect_deserializer =
UntypedReflectDeserializer::new_dynamic(&registry);
  let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;
  
  // OLD
let output: DynamicStruct = reflect_deserializer.deserialize(&mut
deserializer)?.take()?;
  
  // NEW
let output: SomeStruct = reflect_deserializer.deserialize(&mut
deserializer)?.take()?;
  ```

Alternatively, if this behavior isn't desired, use the
`TypedReflectDeserializer::new_dynamic` and
`UntypedReflectDeserializer::new_dynamic` methods instead:

  ```rust
  // OLD
  let reflect_deserializer = UntypedReflectDeserializer::new(&registry);
  
  // NEW
let reflect_deserializer =
UntypedReflectDeserializer::new_dynamic(&registry);
  ```

</details>

---------

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2023-06-29 01:31:34 +00:00
Carter Anderson
aefe1f0739
Schedule-First: the new and improved add_systems (#8079)
Co-authored-by: Mike <mike.hsu@gmail.com>
2023-03-18 01:45:34 +00:00
Gino Valente
d30d3e752a bevy_reflect: Improve serialization format even more (#5723)
> Note: This is rebased off #4561 and can be viewed as a competitor to that PR. See `Comparison with #4561` section for details.

# Objective

The current serialization format used by `bevy_reflect` is both verbose and error-prone. Taking the following structs[^1] for example:

```rust
// -- src/inventory.rs

#[derive(Reflect)]
struct Inventory {
  id: String,
  max_storage: usize,
  items: Vec<Item>
}

#[derive(Reflect)]
struct Item {
  name: String
}
```

Given an inventory of a single item, this would serialize to something like:

```rust
// -- assets/inventory.ron

{
  "type": "my_game::inventory::Inventory",
  "struct": {
    "id": {
      "type": "alloc::string::String",
      "value": "inv001",
    },
    "max_storage": {
      "type": "usize",
      "value": 10
    },
    "items": {
      "type": "alloc::vec::Vec<alloc::string::String>",
      "list": [
        {
          "type": "my_game::inventory::Item",
          "struct": {
            "name": {
              "type": "alloc::string::String",
              "value": "Pickaxe"
            },
          },
        },
      ],
    },
  },
}
```

Aside from being really long and difficult to read, it also has a few "gotchas" that users need to be aware of if they want to edit the file manually. A major one is the requirement that you use the proper keys for a given type. For structs, you need `"struct"`. For lists, `"list"`. For tuple structs, `"tuple_struct"`. And so on.

It also ***requires*** that the `"type"` entry come before the actual data. Despite being a map— which in programming is almost always orderless by default— the entries need to be in a particular order. Failure to follow the ordering convention results in a failure to deserialize the data.

This makes it very prone to errors and annoyances.


## Solution

Using #4042, we can remove a lot of the boilerplate and metadata needed by this older system. Since we now have static access to type information, we can simplify our serialized data to look like:

```rust
// -- assets/inventory.ron

{
  "my_game::inventory::Inventory": (
    id: "inv001",
    max_storage: 10,
    items: [
      (
        name: "Pickaxe"
      ),
    ],
  ),
}
```

This is much more digestible and a lot less error-prone (no more key requirements and no more extra type names).

Additionally, it is a lot more familiar to users as it follows conventional serde mechanics. For example, the struct is represented with `(...)` when serialized to RON.

#### Custom Serialization

Additionally, this PR adds the opt-in ability to specify a custom serde implementation to be used rather than the one created via reflection. For example[^1]:

```rust
// -- src/inventory.rs

#[derive(Reflect, Serialize)]
#[reflect(Serialize)]
struct Item {
  #[serde(alias = "id")]
  name: String
}
```

```rust
// -- assets/inventory.ron

{
  "my_game::inventory::Inventory": (
    id: "inv001",
    max_storage: 10,
    items: [
      (
        id: "Pickaxe"
      ),
    ],
  ),
},
```

By allowing users to define their own serialization methods, we do two things:

1. We give more control over how data is serialized/deserialized to the end user
2. We avoid having to re-define serde's attributes and forcing users to apply both (e.g. we don't need a `#[reflect(alias)]` attribute).

### Improved Formats

One of the improvements this PR provides is the ability to represent data in ways that are more conventional and/or familiar to users. Many users are familiar with RON so here are some of the ways we can now represent data in RON:

###### Structs

```js
{
  "my_crate::Foo": (
    bar: 123
  )
}
// OR
{
  "my_crate::Foo": Foo(
    bar: 123
  )
}
```

<details>
<summary>Old Format</summary>

```js
{
  "type": "my_crate::Foo",
  "struct": {
    "bar": {
      "type": "usize",
      "value": 123
    }
  }
}
```

</details>

###### Tuples

```js
{
  "(f32, f32)": (1.0, 2.0)
}
```

<details>
<summary>Old Format</summary>

```js
{
  "type": "(f32, f32)",
  "tuple": [
    {
      "type": "f32",
      "value": 1.0
    },
    {
      "type": "f32",
      "value": 2.0
    }
  ]
}
```

</details>

###### Tuple Structs

```js
{
  "my_crate::Bar": ("Hello World!")
}
// OR
{
  "my_crate::Bar": Bar("Hello World!")
}
```

<details>
<summary>Old Format</summary>

```js
{
  "type": "my_crate::Bar",
  "tuple_struct": [
    {
      "type": "alloc::string::String",
      "value": "Hello World!"
    }
  ]
}
```

</details>

###### Arrays

It may be a bit surprising to some, but arrays now also use the tuple format. This is because they essentially _are_ tuples (a sequence of values with a fixed size), but only allow for homogenous types. Additionally, this is how RON handles them and is probably a result of the 32-capacity limit imposed on them (both by [serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-%5BT%3B%2032%5D) and by [bevy_reflect](https://docs.rs/bevy/latest/bevy/reflect/trait.GetTypeRegistration.html#impl-GetTypeRegistration-for-%5BT%3B%2032%5D)).

```js
{
  "[i32; 3]": (1, 2, 3)
}
```

<details>
<summary>Old Format</summary>

```js
{
  "type": "[i32; 3]",
  "array": [
    {
      "type": "i32",
      "value": 1
    },
    {
      "type": "i32",
      "value": 2
    },
    {
      "type": "i32",
      "value": 3
    }
  ]
}
```

</details>

###### Enums

To make things simple, I'll just put a struct variant here, but the style applies to all variant types:

```js
{
  "my_crate::ItemType": Consumable(
    name: "Healing potion"
  )
}
```

<details>
<summary>Old Format</summary>

```js
{
  "type": "my_crate::ItemType",
  "enum": {
    "variant": "Consumable",
    "struct": {
      "name": {
        "type": "alloc::string::String",
        "value": "Healing potion"
      }
    }
  }
}
```

</details>

### Comparison with #4561

This PR is a rebased version of #4561. The reason for the split between the two is because this PR creates a _very_ different scene format. You may notice that the PR descriptions for either PR are pretty similar. This was done to better convey the changes depending on which (if any) gets merged first. If #4561 makes it in first, I will update this PR description accordingly.

---

## Changelog

* Re-worked serialization/deserialization for reflected types
* Added `TypedReflectDeserializer` for deserializing data with known `TypeInfo`
* Renamed `ReflectDeserializer` to `UntypedReflectDeserializer` 
* ~~Replaced usages of `deserialize_any` with `deserialize_map` for non-self-describing formats~~ Reverted this change since there are still some issues that need to be sorted out (in a separate PR). By reverting this, crates like `bincode` can throw an error when attempting to deserialize non-self-describing formats (`bincode` results in `DeserializeAnyNotSupported`)
* Structs, tuples, tuple structs, arrays, and enums are now all de/serialized using conventional serde methods

## Migration Guide

* This PR reduces the verbosity of the scene format. Scenes will need to be updated accordingly:

```js
// Old format
{
  "type": "my_game::item::Item",
  "struct": {
    "id": {
      "type": "alloc::string::String",
      "value": "bevycraft:stone",
    },
    "tags": {
      "type": "alloc::vec::Vec<alloc::string::String>",
      "list": [
        {
          "type": "alloc::string::String",
          "value": "material"
        },
      ],
    },
}

// New format
{
  "my_game::item::Item": (
    id: "bevycraft:stone",
    tags: ["material"]
  )
}
```

[^1]: Some derives omitted for brevity.
2022-09-20 19:38:18 +00:00
ira
992681b59b Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577)
*This PR description is an edited copy of #5007, written by @alice-i-cecile.*
# Objective
Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds.

While ergonomic, this results in several drawbacks:

* it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource
* it is challenging to discover if a type is intended to be used as a resource
* we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component).
* dependencies can use the same Rust type as a resource in invisibly conflicting ways
* raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values
* we cannot capture a definitive list of possible resources to display to users in an editor
## Notes to reviewers
 * Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits.
   *ira: My commits are not as well organized :')*
 * I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does.
 * I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981.

## Changelog
`Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro.

## Migration Guide
Add `#[derive(Resource)]` to all types you are using as a resource.

If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics.

`ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing.
Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead.


Co-authored-by: Alice <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: devil-ira <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2022-08-08 21:36:35 +00:00
Gino Valente
15826d6019 bevy_reflect: Reflect enums (#4761)
# Objective

> This is a revival of #1347. Credit for the original PR should go to @Davier.

Currently, enums are treated as `ReflectRef::Value` types by `bevy_reflect`. Obviously, there needs to be better a better representation for enums using the reflection API.

## Solution

Based on prior work from @Davier, an `Enum` trait has been added as well as the ability to automatically implement it via the `Reflect` derive macro. This allows enums to be expressed dynamically:

```rust
#[derive(Reflect)]
enum Foo {
  A,
  B(usize),
  C { value: f32 },
}

let mut foo = Foo::B(123);
assert_eq!("B", foo.variant_name());
assert_eq!(1, foo.field_len());

let new_value = DynamicEnum::from(Foo::C { value: 1.23 });
foo.apply(&new_value);
assert_eq!(Foo::C{value: 1.23}, foo);
```

### Features

#### Derive Macro

Use the `#[derive(Reflect)]` macro to automatically implement the `Enum` trait for enum definitions. Optionally, you can use `#[reflect(ignore)]` with both variants and variant fields, just like you can with structs. These ignored items will not be considered as part of the reflection and cannot be accessed via reflection.

```rust
#[derive(Reflect)]
enum TestEnum {
  A,
  // Uncomment to ignore all of `B`
  // #[reflect(ignore)]
  B(usize),
  C {
    // Uncomment to ignore only field `foo` of `C`
    // #[reflect(ignore)]
    foo: f32,
    bar: bool,
  },
}
```

#### Dynamic Enums

Enums may be created/represented dynamically via the `DynamicEnum` struct. The main purpose of this struct is to allow enums to be deserialized into a partial state and to allow dynamic patching. In order to ensure conversion from a `DynamicEnum` to a concrete enum type goes smoothly, be sure to add `FromReflect` to your derive macro.

```rust
let mut value = TestEnum::A;

// Create from a concrete instance
let dyn_enum = DynamicEnum::from(TestEnum::B(123));

value.apply(&dyn_enum);
assert_eq!(TestEnum::B(123), value);

// Create a purely dynamic instance
let dyn_enum = DynamicEnum::new("TestEnum", "A", ());

value.apply(&dyn_enum);
assert_eq!(TestEnum::A, value);
```

#### Variants

An enum value is always represented as one of its variants— never the enum in its entirety.

```rust
let value = TestEnum::A;
assert_eq!("A", value.variant_name());

// Since we are using the `A` variant, we cannot also be the `B` variant
assert_ne!("B", value.variant_name());
```

All variant types are representable within the `Enum` trait: unit, struct, and tuple.

You can get the current type like:

```rust
match value.variant_type() {
  VariantType::Unit => println!("A unit variant!"),
  VariantType::Struct => println!("A struct variant!"),
  VariantType::Tuple => println!("A tuple variant!"),
}
```

> Notice that they don't contain any values representing the fields. These are purely tags.

If a variant has them, you can access the fields as well:

```rust
let mut value = TestEnum::C {
  foo: 1.23,
  bar: false
};

// Read/write specific fields
*value.field_mut("bar").unwrap() = true;

// Iterate over the entire collection of fields
for field in value.iter_fields() {
  println!("{} = {:?}", field.name(), field.value());
}
```

#### Variant Swapping

It might seem odd to group all variant types under a single trait (why allow `iter_fields` on a unit variant?), but the reason this was done ~~is to easily allow *variant swapping*.~~ As I was recently drafting up the **Design Decisions** section, I discovered that other solutions could have been made to work with variant swapping. So while there are reasons to keep the all-in-one approach, variant swapping is _not_ one of them.

```rust
let mut value: Box<dyn Enum> = Box::new(TestEnum::A);
value.set(Box::new(TestEnum::B(123))).unwrap();
```

#### Serialization

Enums can be serialized and deserialized via reflection without needing to implement `Serialize` or `Deserialize` themselves (which can save thousands of lines of generated code). Below are the ways an enum can be serialized.

> Note, like the rest of reflection-based serialization, the order of the keys in these representations is important!

##### Unit

```json
{
  "type": "my_crate::TestEnum",
  "enum": {
    "variant": "A"
  }
}
```

##### Tuple

```json
{
  "type": "my_crate::TestEnum",
  "enum": {
    "variant": "B",
    "tuple": [
      {
        "type": "usize",
        "value": 123
      }
    ]
  }
}
```

<details>
<summary>Effects on Option</summary>

This ends up making `Option` look a little ugly:

```json
{
  "type": "core::option::Option<usize>",
  "enum": {
    "variant": "Some",
    "tuple": [
      {
        "type": "usize",
        "value": 123
      }
    ]
  }
}
```


</details>

##### Struct

```json
{
  "type": "my_crate::TestEnum",
  "enum": {
    "variant": "C",
    "struct": {
      "foo": {
        "type": "f32",
        "value": 1.23
      },
      "bar": {
        "type": "bool",
        "value": false
      }
    }
  }
}
```

## Design Decisions

<details>
<summary><strong>View Section</strong></summary>

This section is here to provide some context for why certain decisions were made for this PR, alternatives that could have been used instead, and what could be improved upon in the future.

### Variant Representation

One of the biggest decisions was to decide on how to represent variants. The current design uses a "all-in-one" design where unit, tuple, and struct variants are all simultaneously represented by the `Enum` trait. This is not the only way it could have been done, though.

#### Alternatives

##### 1. Variant Traits

One way of representing variants would be to define traits for each variant, implementing them whenever an enum featured at least one instance of them. This would allow us to define variants like:

```rust
pub trait Enum: Reflect {
  fn variant(&self) -> Variant;
}

pub enum Variant<'a> {
    Unit,
    Tuple(&'a dyn TupleVariant),
    Struct(&'a dyn StructVariant),
}

pub trait TupleVariant {
  fn field_len(&self) -> usize;
  // ...
}
```

And then do things like:

```rust
fn get_tuple_len(foo: &dyn Enum) -> usize {
  match foo.variant() {
    Variant::Tuple(tuple) => tuple.field_len(),
    _ => panic!("not a tuple variant!")
  }
}
```

The reason this PR does not go with this approach is because of the fact that variants are not separate types. In other words, we cannot implement traits on specific variants— these cover the *entire* enum. This means we offer an easy footgun:

```rust
let foo: Option<i32> = None;
let my_enum = Box::new(foo) as Box<dyn TupleVariant>;
```

Here, `my_enum` contains `foo`, which is a unit variant. However, since we need to implement `TupleVariant` for `Option` as a whole, it's possible to perform such a cast. This is obviously wrong, but could easily go unnoticed. So unfortunately, this makes it not a good candidate for representing variants.

##### 2. Variant Structs

To get around the issue of traits necessarily needing to apply to both the enum and its variants, we could instead use structs that are created on a per-variant basis. This was also considered but was ultimately [[removed](71d27ab3c6) due to concerns about allocations.

 Each variant struct would probably look something like:

```rust
pub trait Enum: Reflect {
  fn variant_mut(&self) -> VariantMut;
}

pub enum VariantMut<'a> {
    Unit,
    Tuple(TupleVariantMut),
    Struct(StructVariantMut),
}

struct StructVariantMut<'a> {
  fields: Vec<&'a mut dyn Reflect>,
  field_indices: HashMap<Cow<'static, str>, usize>
}
```

This allows us to isolate struct variants into their own defined struct and define methods specifically for their use. It also prevents users from casting to it since it's not a trait. However, this is not an optimal solution. Both `field_indices` and `fields` will require an allocation (remember, a `Box<[T]>` still requires a `Vec<T>` in order to be constructed). This *might* be a problem if called frequently enough.

##### 3. Generated Structs

The original design, implemented by @Davier, instead generates structs specific for each variant. So if we had a variant path like `Foo::Bar`, we'd generate a struct named `FooBarWrapper`. This would be newtyped around the original enum and forward tuple or struct methods to the enum with the chosen variant.

Because it involved using the `Tuple` and `Struct` traits (which are also both bound on `Reflect`), this meant a bit more code had to be generated. For a single struct variant with one field, the generated code amounted to ~110LoC. However, each new field added to that variant only added ~6 more LoC.

In order to work properly, the enum had to be transmuted to the generated struct:

```rust
fn variant(&self) -> crate::EnumVariant<'_> {
  match self {
    Foo::Bar {value: i32} => {
      let wrapper_ref = unsafe { 
        std::mem::transmute::<&Self, &FooBarWrapper>(self) 
      };
      crate::EnumVariant::Struct(wrapper_ref as &dyn crate::Struct)
    }
  }
}
```

This works because `FooBarWrapper` is defined as `repr(transparent)`.

Out of all the alternatives, this would probably be the one most likely to be used again in the future. The reasons for why this PR did not continue to use it was because:

* To reduce generated code (which would hopefully speed up compile times)
* To avoid cluttering the code with generated structs not visible to the user
* To keep bevy_reflect simple and extensible (these generated structs act as proxies and might not play well with current or future systems)
* To avoid additional unsafe blocks
* My own misunderstanding of @Davier's code

That last point is obviously on me. I misjudged the code to be too unsafe and unable to handle variant swapping (which it probably could) when I was rebasing it. Looking over it again when writing up this whole section, I see that it was actually a pretty clever way of handling variant representation.

#### Benefits of All-in-One

As stated before, the current implementation uses an all-in-one approach. All variants are capable of containing fields as far as `Enum` is concerned. This provides a few benefits that the alternatives do not (reduced indirection, safer code, etc.).

The biggest benefit, though, is direct field access. Rather than forcing users to have to go through pattern matching, we grant direct access to the fields contained by the current variant. The reason we can do this is because all of the pattern matching happens internally. Getting the field at index `2` will automatically return `Some(...)` for the current variant if it has a field at that index or `None` if it doesn't (or can't).

This could be useful for scenarios where the variant has already been verified or just set/swapped (or even where the type of variant doesn't matter):

```rust
let dyn_enum: &mut dyn Enum = &mut Foo::Bar {value: 123};
// We know it's the `Bar` variant
let field = dyn_enum.field("value").unwrap();
```

Reflection is not a type-safe abstraction— almost every return value is wrapped in `Option<...>`. There are plenty of places to check and recheck that a value is what Reflect says it is. Forcing users to have to go through `match` each time they want to access a field might just be an extra step among dozens of other verification processes.

 Some might disagree, but ultimately, my view is that the benefit here is an improvement to the ergonomics and usability of reflected enums.

</details>

---

## Changelog

### Added

* Added `Enum` trait
* Added `Enum` impl to `Reflect` derive macro
* Added `DynamicEnum` struct
  * Added `DynamicVariant`
* Added `EnumInfo`
  * Added `VariantInfo`
    * Added `StructVariantInfo`
    * Added `TupleVariantInfo`
    * Added `UnitVariantInfo`
* Added serializtion/deserialization support for enums
  * Added `EnumSerializer`

* Added `VariantType`
* Added `VariantFieldIter`
* Added `VariantField`
* Added `enum_partial_eq(...)`
* Added `enum_hash(...)`

### Changed

* `Option<T>` now implements `Enum`
* `bevy_window` now depends on `bevy_reflect`
  * Implemented `Reflect` and `FromReflect` for `WindowId`
* Derive `FromReflect` on `PerspectiveProjection`
* Derive `FromReflect` on `OrthographicProjection`
* Derive `FromReflect` on `WindowOrigin`
* Derive `FromReflect` on `ScalingMode`
* Derive `FromReflect` on `DepthCalculation`


## Migration Guide

* Enums no longer need to be treated as values and usages of `#[reflect_value(...)]` can be removed or replaced by `#[reflect(...)]`
* Enums (including `Option<T>`) now take a different format when serializing. The format is described above, but this may cause issues for existing scenes that make use of enums. 

---

Also shout out to @nicopap for helping clean up some of the code here! It's a big feature so help like this is really appreciated!

Co-authored-by: Gino Valente <gino.valente.code@gmail.com>
2022-08-02 22:14:41 +00:00
Jakob Hellermann
49ff42cc69 fix new clippy lints (#5160)
# Objective

- Nightly clippy lints should be fixed before they get stable and break CI
  
## Solution

- fix new clippy lints
- ignore `significant_drop_in_scrutinee` since it isn't relevant in our loop https://github.com/rust-lang/rust-clippy/issues/8987
```rust
for line in io::stdin().lines() {
    ...
}
```

Co-authored-by: Jakob Hellermann <hellermann@sipgate.de>
2022-07-01 13:41:23 +00:00
Félix Lescaudey de Maneville
f000c2b951 Clippy improvements (#4665)
# Objective

Follow up to my previous MR #3718 to add new clippy warnings to bevy:

- [x] [~~option_if_let_else~~](https://rust-lang.github.io/rust-clippy/master/#option_if_let_else) (reverted)
- [x] [redundant_else](https://rust-lang.github.io/rust-clippy/master/#redundant_else)
- [x] [match_same_arms](https://rust-lang.github.io/rust-clippy/master/#match_same_arms)
- [x] [semicolon_if_nothing_returned](https://rust-lang.github.io/rust-clippy/master/#semicolon_if_nothing_returned)
- [x] [explicit_iter_loop](https://rust-lang.github.io/rust-clippy/master/#explicit_iter_loop)
- [x] [map_flatten](https://rust-lang.github.io/rust-clippy/master/#map_flatten)

There is one commit per clippy warning, and the matching flags are added to the CI execution.

To test the CI execution you may run `cargo run -p ci -- clippy` at the root.

I choose the add the flags in the `ci` tool crate to avoid having them in every `lib.rs` but I guess it could become an issue with suprise warnings coming up after a commit/push


Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2022-05-31 01:38:07 +00:00
Mark Schmale
1ba7429371 Doc/module style doc blocks for examples (#4438)
# Objective

Provide a starting point for #3951, or a partial solution. 
Providing a few comment blocks to discuss, and hopefully find better one in the process. 

## Solution

Since I am pretty new to pretty much anything in this context, I figured I'd just start with a draft for some file level doc blocks. For some of them I found more relevant details (or at least things I considered interessting), for some others there is less. 

## Changelog

- Moved some existing comments from main() functions in the 2d examples to the file header level
- Wrote some more comment blocks for most other 2d examples

TODO: 
- [x] 2d/sprite_sheet, wasnt able to come up with something good yet 
- [x] all other example groups...


Also: Please let me know if the commit style is okay, or to verbose. I could certainly squash these things, or add more details if needed. 
I also hope its okay to raise this PR this early, with just a few files changed. Took me long enough and I dont wanted to let it go to waste because I lost motivation to do the whole thing. Additionally I am somewhat uncertain over the style and contents of the commets. So let me know what you thing please.
2022-05-16 13:53:20 +00:00
MrGVSV
acbee7795d bevy_reflect: Reflect arrays (#4701)
# Objective

> ℹ️ **Note**: This is a rebased version of #2383. A large portion of it has not been touched (only a few minor changes) so that any additional discussion may happen here. All credit should go to @NathanSWard for their work on the original PR.

- Currently reflection is not supported for arrays.
- Fixes #1213

## Solution

* Implement reflection for arrays via the `Array` trait.
* Note, `Array` is different from `List` in the way that you cannot push elements onto an array as they are statically sized.
* Now `List` is defined as a sub-trait of `Array`.

---

## Changelog

* Added the `Array` reflection trait
* Allows arrays up to length 32 to be reflected via the `Array` trait

## Migration Guide

* The `List` trait now has the `Array` supertrait. This means that `clone_dynamic` will need to specify which version to use:
  ```rust
  // Before
  let cloned = my_list.clone_dynamic();
  // After
  let cloned = List::clone_dynamic(&my_list);
  ```
* All implementers of `List` will now need to implement `Array` (this mostly involves moving the existing methods to the `Array` impl)

Co-authored-by: NathanW <nathansward@comcast.net>
Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-05-13 01:13:30 +00:00
danieleades
d8974e7c3d small and mostly pointless refactoring (#2934)
What is says on the tin.

This has got more to do with making `clippy` slightly more *quiet* than it does with changing anything that might greatly impact readability or performance.

that said, deriving `Default` for a couple of structs is a nice easy win
2022-02-13 22:33:55 +00:00
Michael Dorst
e6bce74220 Fix doc_markdown lints in examples (#3486)
#3457 adds the `doc_markdown` clippy lint, which checks doc comments to make sure code identifiers are escaped with backticks. This causes a lot of lint errors, so this is one of a number of PR's that will fix those lint errors one crate at a time.

This PR fixes lints in the `examples` folder.
2021-12-29 17:25:34 +00:00
François
b724a0f586 Down with the system! (#2496)
# Objective

- Remove all the `.system()` possible.
- Check for remaining missing cases.

## Solution

- Remove all `.system()`, fix compile errors
- 32 calls to `.system()` remains, mostly internals, the few others should be removed after #2446
2021-07-27 23:42:36 +00:00
bjorn3
6d6bc2a8b4 Merge AppBuilder into App (#2531)
This is extracted out of eb8f973646476b4a4926ba644a77e2b3a5772159 and includes some additional changes to remove all references to AppBuilder and fix examples that still used App::build() instead of App::new(). In addition I didn't extract the sub app feature as it isn't ready yet.

You can use `git diff --diff-filter=M eb8f973646476b4a4926ba644a77e2b3a5772159` to find all differences in this PR. The `--diff-filtered=M` filters all files added in the original commit but not in this commit away.

Co-Authored-By: Carter Anderson <mcanders1@gmail.com>
2021-07-27 20:21:06 +00:00
François
e3fb23d4d3 add documentation on LogPlugin and more log usage (#1973)
Fixes #1895 

Changed most `println` to `info` in examples, some to `warn` when it was useful to differentiate from other more noisy logs.

Added doc on `LogPlugin`, how to configure it, and why (and how) you may need to disable it
2021-04-22 23:30:48 +00:00
Carter Anderson
b17f8a4bce format comments (#1612)
Uses the new unstable comment formatting features added to rustfmt.toml.
2021-03-11 00:27:30 +00:00
MinerSebas
8f363544ad Reorder Imports in Examples (#1598)
This only affected 2 Examples:
* `generic_reflection`: For some reason, a `pub use` statement was used. This was removed, and alphabetically ordered.
* `wireframe`: This example used the `bevy_internal` crate directly. Changed to use `bevy` instead.

All other Example Imports are correct.

One potential subjective change is the `removel_detection` example. 
Unlike all other Examples, it has its (first) explanatory comment before the Imports.
2021-03-09 01:07:01 +00:00
TehPers
5e7456115a
Implement Reflect for tuples up to length 12 (#1218)
Add Reflect impls for tuples up to length 12
2021-01-07 19:50:09 -08:00
Carter Anderson
841755aaf2
Adopt a Fetch pattern for SystemParams (#1074) 2020-12-15 21:57:16 -08:00
Nathan Stocks
3cee95e59a
Rename reflect 'hash' method to 'reflect_hash' and partial_eq to reflect_partial_eq (#954)
* Rename reflect 'hash' method to 'reflect_hash' to avoid colliding with std:#️⃣:Hash::hash to resolve #943.

* Rename partial_eq to reflect_partial_eq to avoid collisions with implementations of PartialEq on primitives.
2020-12-01 11:15:07 -08:00
Carter Anderson
72b2fc9843
Bevy Reflection (#926)
Bevy Reflection
2020-11-27 16:39:59 -08:00