6990c0ec24
# Objective - [`thiserror`](https://docs.rs/thiserror/) is used to derive the error type on `bevy_dynamic_plugin`'s [`DynamicPluginLoadError`](https://docs.rs/bevy_dynamic_plugin/latest/bevy_dynamic_plugin/enum.DynamicPluginLoadError.html). - It is an enum where each variant wraps a `libloading` error type. - `thiserror` supports marking this internal error types as `#[source]` so it can automatically fill out the [`Error::source`](https://doc.rust-lang.org/std/error/trait.Error.html#method.source) method. - This allows other error handling libraries to get more information about the error than what Bevy by default provides. It increases interoperability between libraries. ## Solution - Mark the internal `libloading::Error` of `DynamicPluginLoadError` with `#[source]`. --- ## Changelog - Implemented the [`Error::source`](https://doc.rust-lang.org/std/error/trait.Error.html#method.source) method for [`DynamicPluginLoadError`](https://docs.rs/bevy_dynamic_plugin/latest/bevy_dynamic_plugin/enum.DynamicPluginLoadError.html). --- Here is the output from `cargo-expand` before and after the change. ```rust // Before impl Error for DynamicPluginLoadError {} ``` ```rust // After impl Error for DynamicPluginLoadError { fn source(&self) -> Option<&(dyn Error + 'static)> { use thiserror::__private::AsDynError as _; match self { DynamicPluginLoadError::Library { 0: source, .. } => { Some(source.as_dyn_error()) } DynamicPluginLoadError::Plugin { 0: source, .. } => { Some(source.as_dyn_error()) } } } } ```
50 lines
1.8 KiB
Rust
50 lines
1.8 KiB
Rust
use libloading::{Library, Symbol};
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use std::ffi::OsStr;
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use thiserror::Error;
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use bevy_app::{App, CreatePlugin, Plugin};
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/// Errors that can occur when loading a dynamic plugin
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#[derive(Debug, Error)]
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pub enum DynamicPluginLoadError {
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#[error("cannot load library for dynamic plugin: {0}")]
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Library(#[source] libloading::Error),
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#[error("dynamic library does not contain a valid Bevy dynamic plugin")]
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Plugin(#[source] libloading::Error),
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}
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/// Dynamically links a plugin at the given path. The plugin must export a function with the
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/// [`CreatePlugin`] signature named `_bevy_create_plugin`.
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///
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/// # Safety
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///
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/// The specified plugin must be linked against the exact same libbevy.so as this program.
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/// In addition the `_bevy_create_plugin` symbol must not be manually created, but instead created
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/// by deriving `DynamicPlugin` on a unit struct implementing [`Plugin`].
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pub unsafe fn dynamically_load_plugin<P: AsRef<OsStr>>(
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path: P,
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) -> Result<(Library, Box<dyn Plugin>), DynamicPluginLoadError> {
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let lib = Library::new(path).map_err(DynamicPluginLoadError::Library)?;
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let func: Symbol<CreatePlugin> = lib
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.get(b"_bevy_create_plugin")
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.map_err(DynamicPluginLoadError::Plugin)?;
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let plugin = Box::from_raw(func());
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Ok((lib, plugin))
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}
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pub trait DynamicPluginExt {
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/// # Safety
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///
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/// Same as [`dynamically_load_plugin`].
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unsafe fn load_plugin<P: AsRef<OsStr>>(&mut self, path: P) -> &mut Self;
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}
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impl DynamicPluginExt for App {
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unsafe fn load_plugin<P: AsRef<OsStr>>(&mut self, path: P) -> &mut Self {
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let (lib, plugin) = dynamically_load_plugin(path).unwrap();
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std::mem::forget(lib); // Ensure that the library is not automatically unloaded
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plugin.build(self);
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self
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}
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}
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