log_macro

Macro to print variable name and value only (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"]

Implementation

Exported macro code is this:

#[macro_export]
macro_rules! log {
    // Single literal string case
    ( $val:expr $(,)? ) => {{
        if ::std::stringify!($val).starts_with("\"") {
            // Remove quotes for string literals
            ::std::eprintln!("{}", ::std::stringify!($val).trim_matches('\"'));
        } else {
            ::std::eprintln!("{}: {:?}", ::std::stringify!($val), $val);
        }
        $val
    }};

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

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

• add ability to log multiple variables at once as mentioned
• add support for multiple values or different ways of formatting
• get the same level of utilities that Python’s formatted string literals have
  • > print(f”operation: {2+1=}”) -> operation: 2+1=3

♥️

Support on GitHub or look into other projects.