document the try_send!() macro

src/macros.rs

@@ -108,7 +108,30 @@ macro_rules! try_send_error {
 	};
 }
 
-/// Unwrap a `Result<T, E>`, send a message if it's E.
+/// Unwrap a `Result` and return a custom message to send to the client for Err.
+///
+/// # Arguments
+///
+/// * `$i:ident` : `mio::Token` client identifier
+/// * `$e:expr` : Expression to evaluate, must return `Result<T, Box<dyn Error>>`
+/// * `$($arg:tt)*` : Format string and parameters (like `println!()`)
+///
+/// # Example
+///
+/// ```
+/// use std::fs::File;
+/// use mio::Token;
+/// use rude::queue::SendQueue;
+/// use rude::try_send;
+///
+/// fn check_file() -> SendQueue {
+///     let token = Token(12);
+///     let file = try_send!(token, File::open(file!()), "Unable to open {}", file!());
+///     SendQueue::ok(token)
+/// }
+///
+/// # assert_eq!(check_file().0[0].1, SendQueue::ok(Token(12)).0[0].1);
+/// ```
 #[macro_export]
 macro_rules! try_send {
 	($i:ident, $e:expr, $($arg:tt)*) => {