8cdd977a12
# Objective - Make it impossible to add a plugin twice - This is going to be more a risk for plugins with configurations, to avoid things like `App::new().add_plugins(DefaultPlugins).add_plugin(ImagePlugin::default_nearest())` ## Solution - Panic when a plugin is added twice - It's still possible to mark a plugin as not unique by overriding `is_unique` - ~~Simpler version of~~ #3988 (not simpler anymore because of how `PluginGroupBuilder` implements `PluginGroup`)
37 lines
1.5 KiB
Rust
37 lines
1.5 KiB
Rust
use downcast_rs::{impl_downcast, Downcast};
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use crate::App;
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use std::any::Any;
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/// A collection of Bevy app logic and configuration.
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///
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/// Plugins configure an [`App`]. When an [`App`] registers a plugin,
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/// the plugin's [`Plugin::build`] function is run. By default, a plugin
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/// can only be added once to an [`App`].
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///
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/// If the plugin may need to be added twice or more, the function [`is_unique()`](Self::is_unique)
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/// should be overriden to return `false`. Plugins are considered duplicate if they have the same
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/// [`name()`](Self::name). The default `name()` implementation returns the type name, which means
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/// generic plugins with different type parameters will not be considered duplicates.
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pub trait Plugin: Downcast + Any + Send + Sync {
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/// Configures the [`App`] to which this plugin is added.
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fn build(&self, app: &mut App);
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/// Configures a name for the [`Plugin`] which is primarily used for debugging.
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fn name(&self) -> &str {
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std::any::type_name::<Self>()
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}
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/// If the plugin can be meaningfully instantiated several times in an [`App`](crate::App),
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/// override this method to return `false`.
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fn is_unique(&self) -> bool {
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true
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}
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}
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impl_downcast!(Plugin);
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/// A type representing an unsafe function that returns a mutable pointer to a [`Plugin`].
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/// It is used for dynamically loading plugins.
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///
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/// See `bevy_dynamic_plugin/src/loader.rs#dynamically_load_plugin`.
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pub type CreatePlugin = unsafe fn() -> *mut dyn Plugin;
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