Commit graph

13 commits

Author SHA1 Message Date
Coder-Joe458
8f5345573c
Remove manual --cfg docsrs (#14376)
# Objective

- Fixes #14132 

## Solution

- Remove the cfg docsrs
2024-07-22 18:58:04 +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
Gino Valente
aa241672e1
bevy_reflect: Nested TypeInfo getters (#13321)
# Objective

Right now, `TypeInfo` can be accessed directly from a type using either
`Typed::type_info` or `Reflect::get_represented_type_info`.

However, once that `TypeInfo` is accessed, any nested types must be
accessed via the `TypeRegistry`.

```rust
#[derive(Reflect)]
struct Foo {
  bar: usize
}

let registry = TypeRegistry::default();

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

let field = type_info.field("bar").unwrap();

let field_info = registry.get_type_info(field.type_id()).unwrap();
assert!(field_info.is::<usize>());;
```

## Solution

Enable nested types within a `TypeInfo` to be retrieved directly.

```rust
#[derive(Reflect)]
struct Foo {
  bar: usize
}

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

let field = type_info.field("bar").unwrap();

let field_info = field.type_info().unwrap();
assert!(field_info.is::<usize>());;
```

The particular implementation was chosen for two reasons.

Firstly, we can't just store `TypeInfo` inside another `TypeInfo`
directly. This is because some types are recursive and would result in a
deadlock when trying to create the `TypeInfo` (i.e. it has to create the
`TypeInfo` before it can use it, but it also needs the `TypeInfo` before
it can create it). Therefore, we must instead store the function so it
can be retrieved lazily.

I had considered also using a `OnceLock` or something to lazily cache
the info, but I figured we can look into optimizations later. The API
should remain the same with or without the `OnceLock`.

Secondly, a new wrapper trait had to be introduced: `MaybeTyped`. Like
`RegisterForReflection`, this trait is `#[doc(hidden)]` and only exists
so that we can properly handle dynamic type fields without requiring
them to implement `Typed`. We don't want dynamic types to implement
`Typed` due to the fact that it would make the return type
`Option<&'static TypeInfo>` for all types even though only the dynamic
types ever need to return `None` (see #6971 for details).

Users should never have to interact with this trait as it has a blanket
impl for all `Typed` types. And `Typed` is automatically implemented
when deriving `Reflect` (as it is required).

The one downside is we do need to return `Option<&'static TypeInfo>`
from all these new methods so that we can handle the dynamic cases. If
we didn't have to, we'd be able to get rid of the `Option` entirely. But
I think that's an okay tradeoff for this one part of the API, and keeps
the other APIs intact.

## Testing

This PR contains tests to verify everything works as expected. You can
test locally by running:

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

---

## Changelog

### Public Changes

- Added `ArrayInfo::item_info` method
- Added `NamedField::type_info` method
- Added `UnnamedField::type_info` method
- Added `ListInfo::item_info` method
- Added `MapInfo::key_info` method
- Added `MapInfo::value_info` method
- All active fields now have a `Typed` bound (remember that this is
automatically satisfied for all types that derive `Reflect`)

### Internal Changes

- Added `MaybeTyped` trait

## Migration Guide

All active fields for reflected types (including lists, maps, tuples,
etc.), must implement `Typed`. For the majority of users this won't have
any visible impact.

However, users implementing `Reflect` manually may need to update their
types to implement `Typed` if they weren't already.

Additionally, custom dynamic types will need to implement the new hidden
`MaybeTyped` trait.
2024-07-15 00:40:07 +00:00
Gino Valente
99c9218b56
bevy_reflect: Feature-gate function reflection (#14174)
# Objective

Function reflection requires a lot of macro code generation in the form
of several `all_tuples!` invocations, as well as impls generated in the
`Reflect` derive macro.

Seeing as function reflection is currently a bit more niche, it makes
sense to gate it all behind a feature.

## Solution

Add a `functions` feature to `bevy_reflect`, which can be enabled in
Bevy using the `reflect_functions` feature.

## Testing

You can test locally by running:

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

That should ensure that everything still works with the feature
disabled.

To test with the feature on, you can run:

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

---

## Changelog

- Moved function reflection behind a Cargo feature
(`bevy/reflect_functions` and `bevy_reflect/functions`)
- Add `IntoFunction` export in `bevy_reflect::prelude`

## 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.

Function reflection is now gated behind a feature. To use function
reflection, enable the feature:
- If using `bevy_reflect` directly, enable the `functions` feature
- If using `bevy`, enable the `reflect_functions` feature
2024-07-14 15:55:31 +00:00
github-actions[bot]
8df10d2713
Bump Version after Release (#14219)
Bump version after release
This PR has been auto-generated

Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François Mockers <mockersf@gmail.com>
2024-07-08 12:54:08 +00:00
Lura
856b39d821
Apply Clippy lints regarding lazy evaluation and closures (#14015)
# Objective

- Lazily evaluate
[default](https://rust-lang.github.io/rust-clippy/master/index.html#/unwrap_or_default)~~/[or](https://rust-lang.github.io/rust-clippy/master/index.html#/or_fun_call)~~
values where it makes sense
  - ~~`unwrap_or(foo())` -> `unwrap_or_else(|| foo())`~~
  - `unwrap_or(Default::default())` -> `unwrap_or_default()`
  - etc.
- Avoid creating [redundant
closures](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_closure),
even for [method
calls](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_closure_for_method_calls)
  - `map(|something| something.into())` -> `map(Into:into)`

## Solution

- Apply Clippy lints:
-
~~[or_fun_call](https://rust-lang.github.io/rust-clippy/master/index.html#/or_fun_call)~~
-
[unwrap_or_default](https://rust-lang.github.io/rust-clippy/master/index.html#/unwrap_or_default)
-
[redundant_closure_for_method_calls](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_closure_for_method_calls)
([redundant
closures](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_closure)
is already enabled)

## Testing

- Tested on Windows 11 (`stable-x86_64-pc-windows-gnu`, 1.79.0)
- Bevy compiles without errors or warnings and examples seem to work as
intended
  - `cargo clippy` 
  - `cargo run -p ci -- compile` 

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-07-01 15:54:40 +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
faf003fc9d
bevy_reflect: enum_utility cleanup (#13424)
# Objective

The `enum_utility` module contains the `get_variant_constructors`
function, which is used to generate token streams for constructing
enums. It's used for the `FromReflect::from_reflect` implementation and
the `Reflect::try_apply` implementation.

Due to the complexity of enums, this function is understandably a little
messy and difficult to extend.

## Solution

Clean up the `enum_utility` module.

Now "clean" is a bit subjective. I believe my solution is "cleaner" in
that the logic to generate the tokens are strictly coupled with the
intended usage. Because of this, `try_apply` is also no longer strictly
coupled with `from_reflect`.

This makes it easier to extend with new functionality, which is
something I'm doing in a future unrelated PR that I have based off this
one.

## Testing

There shouldn't be any testing required other than ensuring that the
project still builds and that CI passes.
2024-05-22 21:18:57 +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
705c144259
bevy_reflect: Remove ContainerAttributes::merge (#13303)
# Objective

Unblocks #11659.

Currently the `Reflect` derive macro has to go through a merge process
for each `#[reflect]`/`#[reflet_value]` attribute encountered on a
container type.

Not only is this a bit inefficient, but it also has a soft requirement
that we can compare attributes such that an error can be thrown on
duplicates, invalid states, etc.

While working on #11659 this proved to be challenging due to the fact
that `syn` types don't implement `PartialEq` or `Hash` without enabling
the `extra-traits` feature.

Ideally, we wouldn't have to enable another feature just to accommodate
this one use case.

## Solution

Removed `ContainerAttributes::merge`.

This was a fairly simple change as we could just have the parsing
functions take `&mut self` instead of returning `Self`.

## Testing

CI should build as there should be no user-facing change.
2024-05-09 18:17:54 +00:00
Brezak
9c4ac7c297
Finish the work on try_apply (#12646)
# Objective

Finish the `try_apply` implementation started in #6770 by @feyokorenhof.
Supersedes and closes #6770. Closes #6182

## Solution

Add `try_apply` to `Reflect` and implement it in all the places that
implement `Reflect`.

---

## Changelog

Added `try_apply` to `Reflect`.

---------

Co-authored-by: Feyo Korenhof <feyokorenhof@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-05-08 14:26:01 +00:00
BD103
22305acf66
Rename bevy_reflect_derive folder to derive (#13269)
# Objective

- Some of the "large" crates have sub-crates, usually for things such as
macros.
- For an example, see [`bevy_ecs_macros` at
`bevy_ecs/macros`](4f9f987099/crates/bevy_ecs/macros).
- The one crate that does not follow this convention is
[`bevy_reflect_derive`](4f9f987099/crates/bevy_reflect/bevy_reflect_derive),
which is in the `bevy_reflect/bevy_reflect_derive` folder and not
`bevy_reflect/derive` or `bevy_reflect/macros`.

## Solution

- Rename folder `bevy_reflect_derive` to `derive`.
- I chose to use `derive` instead of `macros` because the crate name
itself ends in `_derive`. (One of only two crates to actually use this
convention, funnily enough.)

## Testing

- Build and test `bevy_reflect` and `bevy_reflect_derive`.
- Apply the following patch to `publish.sh` to run it in `--dry-run`
mode, to test that the path has been successfully updated:
- If you have any security concerns about applying random diffs, feel
free to skip this step. Worst case scenario it fails and Cart has to
manually publish a few crates.

```bash
# Apply patch to make `publish.sh` *not* actually publish anything.
git apply path/to/foo.patch
# Make `publish.sh` executable.
chmod +x tools/publish.sh
# Execute `publish.sh`.
./tools/publish.sh
```

```patch
diff --git a/tools/publish.sh b/tools/publish.sh
index b020bad28..fbcc09281 100644
--- a/tools/publish.sh
+++ b/tools/publish.sh
@@ -49,7 +49,7 @@ crates=(
 
 if [ -n "$(git status --porcelain)" ]; then
     echo "You have local changes!"
-    exit 1
+    # exit 1
 fi
 
 pushd crates
@@ -61,15 +61,15 @@ do
   cp ../LICENSE-APACHE "$crate"
   pushd "$crate"
   git add LICENSE-MIT LICENSE-APACHE
-  cargo publish --no-verify --allow-dirty
+  cargo publish --no-verify --allow-dirty --dry-run
   popd
-  sleep 20
+  # sleep 20
 done
 
 popd
 
 echo "Publishing root crate"
-cargo publish --allow-dirty
+cargo publish --allow-dirty --dry-run
 
 echo "Cleaning local state"
 git reset HEAD --hard
```

---

## Changelog

- Moved `bevy_reflect_derive` from
`crates/bevy_reflect/bevy_reflect_derive` to
`crates/bevy_reflect/derive`.
2024-05-07 07:55:32 +00:00