Crate maybe_debug 

maybe-debug

Implement Debug for anything via specialization.

Lets say you have the following function and you want to insert a dbg!() statement inside the loop.

fn sort<T>(target: &mut [T]) {
    for (i, val) in target.iter().enumerate() {
        dbg!(i);
        // various sorting goodness
        dbg!(i, val); // ERROR: T is not Debug
    }
}

You can use maybe_debug::maybe_debug() to work around this. If T is Debug it will ‘cast’ it. If T is !Debug, it will fallback to a reasonable default (printing the type name).

fn sort<T>(target: &mut [T]) {
    for (i, val) in target.iter().enumerate() {
        maybe_debug::dbg!(i);
        // various sorting goodness
        maybe_debug::dbg!(i, val); // On nightly, will specialize if 'T: Debug'
    }
}

This has a fallback to work on stable Rust (without specialization). In that case, the “cast” always fails and maybe_debug will unconditionally use the fallback.

Macros

dbg

A version of std::dbg! that works regardless of whether or not T implements Debug

maybe_dbg

A version of std::dbg! that works regardless of whether or not T implements Debug

Enums

MaybeDebug

Optional presense of Debug information (equivalent to Option<&dyn Debug>)

Functions

cast_debug

Attempt to cast the specified value into &dyn Debug, returning None if this fails.

maybe_debug

Attempt to cast the specified value into &dyn Debug, falling back to a reasonable default on failure.