crates.io

✨ null_fn

A proc attribute macro that allows for creating null function pointers in statics.

Example

```rust static mut UTILPlayerByUserId: unsafe extern "C" fn(userid: i32) -> *mut cvoid = unsafe { std::mem::transmute::<*const (), _>(std::ptr::null()) }; // error[E0080]: it is undefined behavior to use this value

[null_fn]

static mut UTILPlayerByUserId: unsafe extern "C" fn(userid: i32) -> *mut cvoid = std::ptr::null(); // works!

fn main() { unsafe { UTIL_PlayerByUserId(20); // This would panic, as the pointer is NULL.

    let is_null = UTIL_PlayerByUserId.is_null(); // It's just a normal pointer, so we can call pointer-related functions on it.

    UTIL_PlayerByUserId = /* magically find the pointer to the function */;
    let player = UTIL_PlayerByUserId(20); // Now that we set the function pointer, we can call the function without panicking.
}

} ```