Module env_logger::filter[][src]

Filtering for log records.

This module contains the log filtering used by env_logger to match records. You can use the Filter type in your own logger implementation to use the same filter parsing and matching as env_logger. For more details about the format for directive strings see Enabling Logging.

Using env_logger in your own logger

You can use env_logger's filtering functionality with your own logger. Call Builder::parse to parse directives from a string when constructing your logger. Call Filter::matches to check whether a record should be logged based on the parsed filters when log records are received.

extern crate log;
extern crate env_logger;
use env_logger::filter::Filter;
use log::{Log, Metadata, Record};

struct MyLogger {
    filter: Filter

impl MyLogger {
    fn new() -> MyLogger {
        use env_logger::filter::Builder;
        let mut builder = Builder::new();

        // Parse a directives string from an environment variable
        if let Ok(ref filter) = std::env::var("MY_LOG_LEVEL") {

        MyLogger {

impl Log for MyLogger {
    fn enabled(&self, metadata: &Metadata) -> bool {

    fn log(&self, record: &Record) {
        // Check if the record is matched by the filter
        if self.filter.matches(record) {
            println!("{:?}", record);

    fn flush(&self) {}



A builder for a log filter.


A log filter.