log_macro

Macro to print variable(s) with values nicely (stripped from release builds)

Install

cargo add log_macro

Use

Add this to top of file:

#[macro_use]
extern crate log_macro;

Possible uses and outputs:

// print string only
log!("hello"); // -> hello

// print variable
let animals = vec!["cat", "dog"];
log!(animals); // -> animals: ["cat", "dog"]

// print multiple variables
let animals = vec!["cat", "dog"];
let fish = vec!["salmon", "tuna"];
log!(animals, fish);
// each variable logged on new line
// -> animals: ["cat", "dog"]
// -> fish: ["salmon", "tuna"]

Variables will be in green color to stand out.

Implementation

Exported macro code is this:

#[macro_export]
macro_rules! log {
    // Single literal string case
    ( $val:expr $(,)? ) => {{
        #[cfg(debug_assertions)]
        {
            if ::std::stringify!($val).starts_with("\"") {
                // Remove quotes for string literals
                ::std::eprintln!("{}", ::std::stringify!($val).trim_matches('\"'));
            } else {
                // Print using a reference to avoid moving the value
                ::std::eprintln!("\x1B[32m{}\x1B[0m: {:?}", ::std::stringify!($val), &$val);
            }
        }
    }};

    // Multiple variables case
    ( $($val:expr),+ $(,)? ) => {{
        #[cfg(debug_assertions)]
        {
            $(
                $crate::log!($val);
            )+
        }
    }};
}

Run

Will run the tests in src/lib.rs.

cargo watch -q -- sh -c "tput reset && cargo test -q --lib"

Contribute

Always open to useful ideas or fixes in form of issues or PRs.

Can open new issue (search existing issues first) or start discussion.

It's okay to submit draft PR as you can get help along the way to make it merge ready.

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🖤

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