Module log

A lightweight logging facade for Rust.

• Crate ::log.
• docs.rs
• crates.io
• GitHub

log provides a single logging API that abstracts over the actual logging implementation. Libraries can use the logging API provided by this crate, and the executable can choose the logging implementation that is most suitable for its use case.

The log crate provides macros for logging at various levels: error!, warn!, info!, debug!, and trace!, where error! represents the highest priority and trace! the lowest.

The logging facade itself doesn't perform any logging; it needs to be paired with a logging implementation like env_logger, simplelog, fern, or tracing-subscriber. The implementation is responsible for filtering log messages, formatting them, and outputting them to the appropriate destination.

Examples

use log::{debug, error, info, trace, warn};

fn main() {
    env_logger::init();

    process_data(42);
}

fn process_data(value: i32) {
    trace!("Starting data processing");
    debug!("Processing value: {}", value);

    if value < 0 {
        error!("Invalid value: {}", value);
        return;
    }

    if value == 0 {
        warn!("Processing zero value");
    }

    info!("Successfully processed value: {}", value);
}