Add Application::Executor associated type

src/application.rs

@@ -1,4 +1,4 @@
-use crate::{window, Command, Element, Settings, Subscription};
+use crate::{window, Command, Element, Executor, Settings, Subscription};
 
 /// An interactive cross-platform application.
 ///
@@ -19,7 +19,7 @@ use crate::{window, Command, Element, Settings, Subscription};
 /// before](index.html#overview). We just need to fill in the gaps:
 ///
 /// ```no_run
-/// use iced::{button, Application, Button, Column, Command, Element, Settings, Text};
+/// use iced::{button, executor, Application, Button, Column, Command, Element, Settings, Text};
 ///
 /// pub fn main() {
 ///     Counter::run(Settings::default())
@@ -39,6 +39,7 @@ use crate::{window, Command, Element, Settings, Subscription};
 /// }
 ///
 /// impl Application for Counter {
+///     type Executor = executor::Null;
 ///     type Message = Message;
 ///
 ///     fn new() -> (Self, Command<Message>) {
@@ -80,6 +81,14 @@ use crate::{window, Command, Element, Settings, Subscription};
 /// }
 /// ```
 pub trait Application: Sized {
+    /// The [`Executor`] that will run commands and subscriptions.
+    ///
+    /// The [`executor::Default`] can be a good starting point!
+    ///
+    /// [`Executor`]: trait.Executor.html
+    /// [`executor::Default`]: executor/struct.Default.html
+    type Executor: Executor;
+
     /// The type of __messages__ your [`Application`] will produce.
     ///
     /// [`Application`]: trait.Application.html
@@ -185,6 +194,7 @@ where
     A: Application,
 {
     type Renderer = iced_wgpu::Renderer;
+    type Executor = A::Executor;
     type Message = A::Message;
 
     fn new() -> (Self, Command<A::Message>) {

src/lib.rs

@@ -180,18 +180,26 @@
 #![deny(unsafe_code)]
 #![deny(rust_2018_idioms)]
 mod application;
-#[cfg(target_arch = "wasm32")]
-#[path = "web.rs"]
-mod platform;
-#[cfg(not(target_arch = "wasm32"))]
-#[path = "native.rs"]
-mod platform;
 mod sandbox;
 
+#[cfg(not(target_arch = "wasm32"))]
+mod native;
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use native::*;
+
+#[cfg(target_arch = "wasm32")]
+mod web;
+
+#[cfg(target_arch = "wasm32")]
+pub use web::*;
+
 pub mod settings;
 pub mod window;
 
+#[doc(no_inline)]
+pub use executor::Executor;
+
 pub use application::Application;
-pub use platform::*;
 pub use sandbox::Sandbox;
 pub use settings::Settings;

src/native.rs

@@ -3,6 +3,8 @@ pub use iced_winit::{
     Space, Subscription, Vector, VerticalAlignment,
 };
 
+pub mod executor;
+
 pub mod widget {
     //! Display information and interactive controls in your application.
     //!

src/native/executor.rs

@@ -0,0 +1,23 @@
+//! Choose your preferred executor to power your application.
+pub use iced_winit::{executor::Null, Executor};
+use iced_winit::{executor::ThreadPool, futures};
+
+/// The default cross-platform executor.
+///
+/// - On native platforms, it will use a `ThreadPool`.
+/// - On the Web, it will use `wasm-bindgen-futures::spawn_local`.
+#[derive(Debug)]
+pub struct Default(ThreadPool);
+
+impl Executor for Default {
+    fn new() -> Result<Self, futures::io::Error> {
+        Ok(Default(ThreadPool::new()?))
+    }
+
+    fn spawn(
+        &self,
+        future: impl futures::Future<Output = ()> + Send + 'static,
+    ) {
+        self.0.spawn(future);
+    }
+}

src/sandbox.rs

@@ -1,4 +1,4 @@
-use crate::{Application, Command, Element, Settings, Subscription};
+use crate::{executor, Application, Command, Element, Settings, Subscription};
 
 /// A sandboxed [`Application`].
 ///
@@ -133,6 +133,7 @@ impl<T> Application for T
 where
     T: Sandbox,
 {
+    type Executor = executor::Null;
     type Message = T::Message;
 
     fn new() -> (Self, Command<T::Message>) {