Re-work event loop run() API so it can return a Result

This re-works the portable `run()` API that consumes the `EventLoop` and runs the loop on the calling thread until the app exits. This can be supported across _all_ platforms and compared to the previous `run() -> !` API is now able to return a `Result` status on all platforms except iOS and Web. Fixes: rust-windowing#2709 By moving away from `run() -> !` we stop calling `std::process::exit()` internally as a means to kill the process without returning which means it's possible to return an exit status and applications can return from their `main()` function normally. This also fixes Android support where an Activity runs in a thread but we can't assume to have full ownership of the process (other services could be running in separate threads). Additionally all examples have generally been updated so that `main()` returns a `Result` from `run()` Fixes: rust-windowing#2709
rib · Jun 18, 2023 · 23e7376 · 23e7376
1 parent c2cc308
commit 23e7376
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Showing 35 changed files with 87 additions and 108 deletions.
diff --git a/examples/child_window.rs b/examples/child_window.rs
@@ -1,5 +1,5 @@
 #[cfg(any(x11_platform, macos_platform, windows_platform))]
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     use std::collections::HashMap;
 
     use raw_window_handle::HasRawWindowHandle;

diff --git a/examples/control_flow.rs b/examples/control_flow.rs
@@ -20,7 +20,7 @@ enum Mode {
 const WAIT_TIME: time::Duration = time::Duration::from_millis(100);
 const POLL_SLEEP_TIME: time::Duration = time::Duration::from_millis(100);
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
 
     println!("Press '1' to switch to Wait mode.");
@@ -113,5 +113,5 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/cursor.rs b/examples/cursor.rs
@@ -7,7 +7,7 @@ use winit::{
     window::{CursorIcon, WindowBuilder},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -48,7 +48,7 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
 
 const CURSORS: &[CursorIcon] = &[

diff --git a/examples/cursor_grab.rs b/examples/cursor_grab.rs
@@ -8,7 +8,7 @@ use winit::{
     window::{CursorGrabMode, WindowBuilder},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -69,5 +69,5 @@ fn main() {
             },
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/custom_events.rs b/examples/custom_events.rs
@@ -1,7 +1,7 @@
 #![allow(clippy::single_match)]
 
 #[cfg(not(wasm_platform))]
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     use simple_logger::SimpleLogger;
     use winit::{
         event::{Event, WindowEvent},
@@ -46,7 +46,7 @@ fn main() {
             } => control_flow.set_exit(),
             _ => (),
         }
-    });
+    })
 }
 
 #[cfg(wasm_platform)]

diff --git a/examples/drag_window.rs b/examples/drag_window.rs
@@ -8,7 +8,7 @@ use winit::{
     window::{Window, WindowBuilder, WindowId},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -59,7 +59,7 @@ fn main() {
             _ => (),
         },
         _ => (),
-    });
+    })
 }
 
 fn name_windows(window_id: WindowId, switched: bool, window_1: &Window, window_2: &Window) {

diff --git a/examples/fullscreen.rs b/examples/fullscreen.rs
@@ -9,7 +9,7 @@ use winit::window::{Fullscreen, WindowBuilder};
 #[cfg(target_os = "macos")]
 use winit::platform::macos::WindowExtMacOS;
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -125,5 +125,5 @@ fn main() {
             },
             _ => {}
         }
-    });
+    })
 }
diff --git a/examples/handling_close.rs b/examples/handling_close.rs
@@ -8,7 +8,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -81,5 +81,5 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/ime.rs b/examples/ime.rs
@@ -10,7 +10,7 @@ use winit::{
     window::{ImePurpose, WindowBuilder},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new()
         .with_level(LevelFilter::Trace)
         .init()
@@ -99,5 +99,5 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/key_binding.rs b/examples/key_binding.rs
@@ -17,7 +17,7 @@ fn main() {
 }
 
 #[cfg(any(target_os = "macos", target_os = "windows", target_os = "linux"))]
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     simple_logger::SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -55,5 +55,5 @@ fn main() {
             },
             _ => (),
         };
-    });
+    })
 }
diff --git a/examples/mouse_wheel.rs b/examples/mouse_wheel.rs
@@ -7,7 +7,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -58,5 +58,5 @@ In other words, the deltas indicate the direction in which to move the content (
             },
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/multithreaded.rs b/examples/multithreaded.rs
@@ -1,7 +1,7 @@
 #![allow(clippy::single_match)]
 
 #[cfg(not(wasm_platform))]
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     use std::{collections::HashMap, sync::mpsc, thread, time::Duration};
 
     use simple_logger::SimpleLogger;

diff --git a/examples/multiwindow.rs b/examples/multiwindow.rs
@@ -10,7 +10,7 @@ use winit::{
     window::Window,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 

diff --git a/examples/request_redraw.rs b/examples/request_redraw.rs
@@ -7,7 +7,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -37,5 +37,5 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/request_redraw_threaded.rs b/examples/request_redraw_threaded.rs
@@ -1,7 +1,7 @@
 #![allow(clippy::single_match)]
 
 #[cfg(not(wasm_platform))]
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     use std::{thread, time};
 
     use simple_logger::SimpleLogger;
@@ -39,7 +39,7 @@ fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
 
 #[cfg(wasm_platform)]

diff --git a/examples/resizable.rs b/examples/resizable.rs
@@ -9,7 +9,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -47,5 +47,5 @@ fn main() {
             },
             _ => (),
         };
-    });
+    })
 }
diff --git a/examples/theme.rs b/examples/theme.rs
@@ -8,7 +8,7 @@ use winit::{
     window::{Theme, WindowBuilder},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -68,5 +68,5 @@ fn main() {
             },
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/timer.rs b/examples/timer.rs
@@ -10,7 +10,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -38,5 +38,5 @@ fn main() {
             } => control_flow.set_exit(),
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/touchpad_gestures.rs b/examples/touchpad_gestures.rs
@@ -5,7 +5,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -42,5 +42,5 @@ fn main() {
                 _ => (),
             }
         }
-    });
+    })
 }
diff --git a/examples/transparent.rs b/examples/transparent.rs
@@ -7,7 +7,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -30,5 +30,5 @@ fn main() {
             } => control_flow.set_exit(),
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/web.rs b/examples/web.rs
@@ -6,7 +6,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-pub fn main() {
+pub fn main() -> std::result::Result<(), impl std::error::Error> {
     let event_loop = EventLoop::new();
 
     let window = WindowBuilder::new()
@@ -33,7 +33,7 @@ pub fn main() {
             }
             _ => (),
         }
-    });
+    })
 }
 
 #[cfg(wasm_platform)]

diff --git a/examples/window.rs b/examples/window.rs
@@ -7,7 +7,7 @@ use winit::{
     window::WindowBuilder,
 };
 
-fn main() {
+fn main() -> Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -25,11 +25,14 @@ fn main() {
             Event::WindowEvent {
                 event: WindowEvent::CloseRequested,
                 window_id,
-            } if window_id == window.id() => control_flow.set_exit(),
+            } if window_id == window.id() => {
+                log::warn!("Close button pressed");
+                control_flow.set_exit()
+            }
             Event::MainEventsCleared => {
                 window.request_redraw();
             }
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/window_buttons.rs b/examples/window_buttons.rs
@@ -11,7 +11,7 @@ use winit::{
     window::{WindowBuilder, WindowButtons},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -65,5 +65,5 @@ fn main() {
             } if window_id == window.id() => control_flow.set_exit(),
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/window_debug.rs b/examples/window_debug.rs
@@ -11,7 +11,7 @@ use winit::{
     window::{Fullscreen, WindowBuilder},
 };
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -133,5 +133,5 @@ fn main() {
             } if window_id == window.id() => control_flow.set_exit(),
             _ => (),
         }
-    });
+    })
 }
diff --git a/examples/window_drag_resize.rs b/examples/window_drag_resize.rs
@@ -10,7 +10,7 @@ use winit::{
 
 const BORDER: f64 = 8.0;
 
-fn main() {
+fn main() -> std::result::Result<(), impl std::error::Error> {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
@@ -66,7 +66,7 @@ fn main() {
             _ => (),
         },
         _ => (),
-    });
+    })
 }
 
 fn cursor_direction_icon(resize_direction: Option<ResizeDirection>) -> CursorIcon {