mirror of
https://github.com/bevyengine/bevy
synced 2024-11-22 20:53:53 +00:00
b724a0f586
# 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
98 lines
3.8 KiB
Rust
98 lines
3.8 KiB
Rust
use bevy::{
|
|
prelude::*,
|
|
reflect::{
|
|
serde::{ReflectDeserializer, ReflectSerializer},
|
|
DynamicStruct, TypeRegistry,
|
|
},
|
|
};
|
|
use serde::de::DeserializeSeed;
|
|
|
|
/// This example illustrates how "reflection" works in Bevy. Reflection provide a way to dynamically
|
|
/// interact with Rust types, such as accessing fields by their string name. Reflection is a core
|
|
/// part of Bevy and enables a number of interesting scenarios (like scenes).
|
|
fn main() {
|
|
App::new()
|
|
.add_plugins(DefaultPlugins)
|
|
.register_type::<Foo>()
|
|
.register_type::<Bar>()
|
|
.add_startup_system(setup)
|
|
.run();
|
|
}
|
|
|
|
/// Deriving `Reflect` implements the relevant reflection traits. In this case, it implements the
|
|
/// `Reflect` trait and the `Struct` trait `derive(Reflect)` assumes that all fields also implement
|
|
/// Reflect.
|
|
#[derive(Reflect)]
|
|
pub struct Foo {
|
|
a: usize,
|
|
nested: Bar,
|
|
#[reflect(ignore)]
|
|
_ignored: NonReflectedValue,
|
|
}
|
|
|
|
/// This `Bar` type is used in the `nested` field on the `Test` type. We must derive `Reflect` here
|
|
/// too (or ignore it)
|
|
#[derive(Reflect)]
|
|
pub struct Bar {
|
|
b: usize,
|
|
}
|
|
|
|
pub struct NonReflectedValue {
|
|
_a: usize,
|
|
}
|
|
|
|
fn setup(type_registry: Res<TypeRegistry>) {
|
|
let mut value = Foo {
|
|
a: 1,
|
|
_ignored: NonReflectedValue { _a: 10 },
|
|
nested: Bar { b: 8 },
|
|
};
|
|
|
|
// You can set field values like this. The type must match exactly or this will fail.
|
|
*value.get_field_mut("a").unwrap() = 2usize;
|
|
assert_eq!(value.a, 2);
|
|
assert_eq!(*value.get_field::<usize>("a").unwrap(), 2);
|
|
|
|
// You can also get the &dyn Reflect value of a field like this
|
|
let field = value.field("a").unwrap();
|
|
|
|
// you can downcast Reflect values like this:
|
|
assert_eq!(*field.downcast_ref::<usize>().unwrap(), 2);
|
|
|
|
// DynamicStruct also implements the `Struct` and `Reflect` traits.
|
|
let mut patch = DynamicStruct::default();
|
|
patch.insert("a", 4usize);
|
|
|
|
// You can "apply" Reflect implementations on top of other Reflect implementations.
|
|
// This will only set fields with the same name, and it will fail if the types don't match.
|
|
// You can use this to "patch" your types with new values.
|
|
value.apply(&patch);
|
|
assert_eq!(value.a, 4);
|
|
|
|
let type_registry = type_registry.read();
|
|
// By default, all derived `Reflect` types can be Serialized using serde. No need to derive
|
|
// Serialize!
|
|
let serializer = ReflectSerializer::new(&value, &type_registry);
|
|
let ron_string =
|
|
ron::ser::to_string_pretty(&serializer, ron::ser::PrettyConfig::default()).unwrap();
|
|
info!("{}\n", ron_string);
|
|
|
|
// Dynamic properties can be deserialized
|
|
let reflect_deserializer = ReflectDeserializer::new(&type_registry);
|
|
let mut deserializer = ron::de::Deserializer::from_str(&ron_string).unwrap();
|
|
let reflect_value = reflect_deserializer.deserialize(&mut deserializer).unwrap();
|
|
|
|
// Deserializing returns a Box<dyn Reflect> value. Generally, deserializing a value will return
|
|
// the "dynamic" variant of a type. For example, deserializing a struct will return the
|
|
// DynamicStruct type. "Value types" will be deserialized as themselves.
|
|
let _deserialized_struct = reflect_value.downcast_ref::<DynamicStruct>();
|
|
|
|
// Reflect has its own `partial_eq` implementation, named `reflect_partial_eq`. This behaves
|
|
// like normal `partial_eq`, but it treats "dynamic" and "non-dynamic" types the same. The
|
|
// `Foo` struct and deserialized `DynamicStruct` are considered equal for this reason:
|
|
assert!(reflect_value.reflect_partial_eq(&value).unwrap());
|
|
|
|
// By "patching" `Foo` with the deserialized DynamicStruct, we can "Deserialize" Foo.
|
|
// This means we can serialize and deserialize with a single `Reflect` derive!
|
|
value.apply(&*reflect_value);
|
|
}
|