Macro simple_error::require_with
source · macro_rules! require_with { ($expr: expr, $fmt:literal) => { ... }; ($expr: expr, $str: expr) => { ... }; ($expr: expr, $fmt:literal, $($arg:tt)+) => { ... }; }
Expand description
Helper macro for unwrapping Option
values while returning early with a
newly constructed SimpleError
if the value of the expression is None
.
Can only be used in functions that return Result<_, SimpleError>
.
Examples
use self::simple_error::SimpleError;
use std::error::Error;
fn require_block(maybe: Option<()>, s: &str) -> Result<(), SimpleError> {
Ok(require_with!(maybe, s))
}
// Above is equivalent to below.
fn require_block_equivalent(maybe: Option<()>, s: &str) -> Result<(), SimpleError> {
match maybe {
Some(v) => Ok(v),
None => {
return Err(SimpleError::new(s));
},
}
}
// Use a format string
fn require_block_format(maybe: Option<()>, s: &str) -> Result<(), SimpleError> {
Ok(require_with!(maybe, "with {}", s))
}
// Use a format string to a boxed error
fn require_block_format_to_box_error(maybe: Option<()>, s: &str) -> Result<(), Box<dyn Error>> {
Ok(require_with!(maybe, "with {}", s))
}