Crate safe_unwrap [] [src]

Annotate unwraps as manually checked

The safe_unwrap macros allows unwrapping and annotating that the unwrap will never fail.

An example:

#[macro_use]
extern crate safe_unwrap;

fn main() {
   let res = Some(42);

   // we know that unwrapping res will never fail, so it is safe to call unwrap
   let val = safe_unwrap!("is constant value", res);

   assert_eq!(val, 42);
}

In release builds, safe_unwrap!(expr) is equivalent to expr.unwrap(); in debug builds, expect() will be called with a message indicating that the assumed invariant has been violated.

Alternative, for Result and Option types, you can risk a small bit of overhead in exchange for nicer syntax:

extern crate safe_unwrap;
use safe_unwrap::SafeUnwrap;

fn main() {
   let res = Some(42);

   // works only for Result and Option types
   let val = res.safe_unwrap("is constant value");

   assert_eq!(val, 42);
}

The semantics of .safe_unwrap are otherwise the same as the safe_unwrap! macro. The tradeoff here is that you are at the mercy of the LLVM optimizer to remove the unused static string "is constant value" from the resulting executable (often works in release mode).

Does not require std.

Macros

safe_unwrap

Traits

SafeUnwrap