Struct fern::Panic

pub struct Panic;

Logger which will panic whenever anything is logged. The panic will be exactly the message of the log.

Panic is useful primarily as a secondary logger, filtered by warning or error.

Examples

This configuration will output all messages to stdout and panic if an Error message is sent.

fern::Dispatch::new()
    // format, etc.
    .chain(std::io::stdout())
    .chain(
        fern::Dispatch::new()
            .level(log::LevelFilter::Error)
            .chain(fern::Panic)
    )
    .apply()?;

This function sets up a "panic on warn+" logger, and ignores the error if it has been set up before. One could call this in test functions, for example, to error on warn-level messages.

fn setup_panic_logging() {
    fern::Dispatch::new()
        .level(log::LevelFilter::Warn)
        .chain(fern::Panic)
        .apply()
        .ok(); // ignore result - it's ok if we try to set this up multiple times
}