From ce98a4755ee58bbb589784722027e211d3fa5208 Mon Sep 17 00:00:00 2001
From: Marijn Suijten <marijns95@gmail.com>
Date: Fri, 27 Oct 2023 21:02:20 +0200
Subject: [PATCH] examples: Return `anyhow::Result` out of `main()`

It is annoying to see only a single line of error when debugging a chain
of (e.g. `anyhow::Context::context()`-created) errors, and have a
zero exit-code while at it.

Instead Rust supports returning a `Result` type straight from main which
is `Debug`- instead of `Display`-printed, so that - in the case of
`anyhow::Error` - all nested (via `.source()`) `Error`s are printed in
backtrace-like form, and the exit code is appropriately non-zero.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1336>
---
 examples/src/bin/glfilter.rs | 12 ++++++------
 examples/src/bin/glwindow.rs | 12 ++++++------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/examples/src/bin/glfilter.rs b/examples/src/bin/glfilter.rs
index cd19d409d..1f90c1a9c 100644
--- a/examples/src/bin/glfilter.rs
+++ b/examples/src/bin/glfilter.rs
@@ -1,5 +1,7 @@
 #![allow(clippy::non_send_fields_in_send_ty)]
 
+use anyhow::Result;
+
 #[path = "../glupload.rs"]
 mod glupload;
 use glupload::*;
@@ -161,14 +163,12 @@ mod mirror {
     }
 }
 
-fn example_main() {
+fn example_main() -> Result<()> {
     gst::init().unwrap();
     let glfilter = mirror::GLMirrorFilter::new(Some("foo"));
-    App::new(Some(glfilter.as_ref()))
-        .and_then(main_loop)
-        .unwrap_or_else(|e| eprintln!("Error! {e}"))
+    App::new(Some(glfilter.as_ref())).and_then(main_loop)
 }
 
-fn main() {
-    examples_common::run(example_main);
+fn main() -> Result<()> {
+    examples_common::run(example_main)
 }
diff --git a/examples/src/bin/glwindow.rs b/examples/src/bin/glwindow.rs
index 8ccaae4b2..6c1b5b144 100644
--- a/examples/src/bin/glwindow.rs
+++ b/examples/src/bin/glwindow.rs
@@ -1,5 +1,7 @@
 #![allow(clippy::non_send_fields_in_send_ty)]
 
+use anyhow::Result;
+
 #[path = "../glupload.rs"]
 mod glupload;
 use glupload::*;
@@ -7,12 +9,10 @@ use glupload::*;
 #[path = "../examples-common.rs"]
 pub mod examples_common;
 
-fn example_main() {
-    App::new(None)
-        .and_then(main_loop)
-        .unwrap_or_else(|e| eprintln!("Error! {e}"))
+fn example_main() -> Result<()> {
+    App::new(None).and_then(main_loop)
 }
 
-fn main() {
-    examples_common::run(example_main);
+fn main() -> Result<()> {
+    examples_common::run(example_main)
 }