macro_rules! ensure { ($cond:expr, $msg:literal $(,)?) => { ... }; ($cond:expr, $msg:expr $(,)?) => { ... }; ($cond:expr, $msg:expr, $($arg:tt)*) => { ... }; }
Expand description
Return early with an error if a condition is not satisfied.
This macro is equivalent to if !$cond { return Err(From::from($err)); }.
Analogously to assert!, ensure! takes a condition and exits the function
if the condition fails. Unlike assert!, ensure! returns an Error
rather than panicking.