Debugging Special Code ​

In some cases it may be good to have special algorithms that exist only in debug and do not affect the actual operation of the program, but disappear in production compilation. This section tells you how to get them.

Debugging Outputs ​

Debugging outputs are calls that contain information to help you while debugging or provide some data for some reason. In fact, they are the equivalent of the built-in out and outln functions, but they are not included in the production compilation.

They are defined in the std::debug standard library and must be imported to be used.

For example:

use debug for std::debug

fn main() {
    outln("I am always here")
    debug::Outln("I will not be here in production builds")
}

Debugging Special Algorithms ​

The call function provided by std::debug calls the given function immediately at no additional cost. This call is eliminated in production compilation. Using this call you can implement some of your algorithms required for debugging.

For example:

use debug for std::debug

fn getMagicNumber(): int { ret 42 }

fn main() {
    let x = getMagicNumber()
    debug::Call(fn() {
        if x == 20 {
            panic("Magic number is 20, and I do not like this")
        }
    })
    outln(x)
}