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

The tasks to do are outlined in existing issues and in tasks below (sorted by priority).

If issue/idea you have is not there, open new issue or start discussion.

Any PR with code/doc improvements is welcome. ✨

Join Discord for more indepth discussions on this repo and others.

Tasks

• fix docset for the macro export, nothing is showing
  • there are some errors present after running cargo test --doc --package log_macro -- log --nocapture. fix them
• fix the tests
  • currently they fail as I am not sure how to actually test that the logs are as they are
  • GPT says to try use duct potentially but that gave some issues
• add support for multiple values or different ways of formatting
  • not sure what author meant, investigate
• get the same level of utilities that Python’s formatted string literals have
  • > print(f”operation: {2+1=}”) -> operation: 2+1=3
• decide if macro should be stripped from release builds or not
  • currently it's stripped similar to dbg!
  • potentially provide another near identical macro to keep similar logs but also in release mode?

♥️

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