log::log_enabled!

macro_rules! log_enabled {
    (target: $target:expr, $lvl:expr) => ({
        let lvl = $lvl;
        !cfg!(log_level = "off") &&
            (lvl <= $crate::LogLevel::Error || !cfg!(log_level = "error")) &&
            (lvl <= $crate::LogLevel::Warn || !cfg!(log_level = "warn")) &&
            (lvl <= $crate::LogLevel::Debug || !cfg!(log_level = "debug")) &&
            (lvl <= $crate::LogLevel::Info || !cfg!(log_level = "info")) &&
            lvl <= $crate::max_log_level() &&
            $crate::__enabled(lvl, $target)
    });
    ($lvl:expr) => (log_enabled!(target: module_path!(), $lvl))
}

Determines if a message logged at the specified level in that module will be logged.

This can be used to avoid expensive computation of log message arguments if the message would be ignored anyway.

Examples

use log::LogLevel::Debug;

if log_enabled!(Debug) {
    debug!("expensive debug data: {}", expensive_call());
}