debuggingrustdebug-print

Does Rust have a debug macro?

In C++, I use something like this DEBUG macro:

#ifdef DEBUG
#define DEBUG_STDERR(x) (std::cerr << (x))
#define DEBUG_STDOUT(x) (std::cout << (x))
#else 
#define DEBUG_STDERR(x)
#define DEBUG_STDOUT(x)
#endif

Does Rust have something similar?

Solution

  • Although it makes sense to use something like the log crate as mentioned in DK's answer, here's how to do the direct equivalent of what you asked:

    // The debug version
#[cfg(feature = "my_debug")]
macro_rules! debug_print {
    ($( $args:expr ),*) => { println!( $( $args ),* ); }
}

// Non-debug version
#[cfg(not(feature = "my_debug"))]
macro_rules! debug_print {
    ($( $args:expr ),*) => {}
}

fn main() {
    debug_print!("Debug only {}", 123);
}

    And in your Cargo.toml, add a [features] section:

    [features]
my_debug = []

    The output then appears with cargo run --features my_debug, and doesn't with a plain cargo run.