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/// Convenient wrapper to be able to use `?` and such in the main. You can
/// use it with a separated function:
///
/// ```
/// # #[macro_use] extern crate error_chain;
/// # error_chain! {}
/// # fn main() {
/// quick_main!(run);
/// # }
///
/// fn run() -> Result<()> {
/// Err("error".into())
/// }
/// ```
///
/// or with a closure:
///
/// ```
/// # #[macro_use] extern crate error_chain;
/// # error_chain! {}
/// # fn main() {
/// quick_main!(|| -> Result<()> {
/// Err("error".into())
/// });
/// # }
/// ```
///
/// You can also set the exit value of the process by returning a type that implements [`ExitCode`](trait.ExitCode.html):
///
/// ```
/// # #[macro_use] extern crate error_chain;
/// # error_chain! {}
/// # fn main() {
/// quick_main!(run);
/// # }
///
/// fn run() -> Result<i32> {
/// Err("error".into())
/// }
/// ```
#[macro_export]
macro_rules! quick_main {
($main:expr) => {
fn main() {
use std::io::Write;
::std::process::exit(match $main() {
Ok(ret) => $crate::ExitCode::code(ret),
Err(ref e) => {
write!(
&mut ::std::io::stderr(),
"{}",
$crate::ChainedError::display_chain(e)
)
.expect("Error writing to stderr");
1
}
});
}
};
}
/// Represents a value that can be used as the exit status of the process.
/// See [`quick_main!`](macro.quick_main.html).
pub trait ExitCode {
/// Returns the value to use as the exit status.
fn code(self) -> i32;
}
impl ExitCode for i32 {
fn code(self) -> i32 {
self
}
}
impl ExitCode for () {
fn code(self) -> i32 {
0
}
}
|
