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+/*!
+Using `env_logger` to drive a custom logger.
+
+Before running this example, try setting the `MY_LOG_LEVEL` environment variable to `info`:
+
+```no_run,shell
+$ export MY_LOG_LEVEL='info'
+```
+
+If you only want to change the way logs are formatted, look at the `custom_format` example.
+*/
+
+#[macro_use]
+extern crate log;
+
+use env_logger::filter::{Builder, Filter};
+
+use log::{Log, Metadata, Record, SetLoggerError};
+
+const FILTER_ENV: &str = "MY_LOG_LEVEL";
+
+struct MyLogger {
+ inner: Filter,
+}
+
+impl MyLogger {
+ fn new() -> MyLogger {
+ let mut builder = Builder::from_env(FILTER_ENV);
+
+ MyLogger {
+ inner: builder.build(),
+ }
+ }
+
+ fn init() -> Result<(), SetLoggerError> {
+ let logger = Self::new();
+
+ log::set_max_level(logger.inner.filter());
+ log::set_boxed_logger(Box::new(logger))
+ }
+}
+
+impl Log for MyLogger {
+ fn enabled(&self, metadata: &Metadata) -> bool {
+ self.inner.enabled(metadata)
+ }
+
+ fn log(&self, record: &Record) {
+ // Check if the record is matched by the logger before logging
+ if self.inner.matches(record) {
+ println!("{} - {}", record.level(), record.args());
+ }
+ }
+
+ fn flush(&self) {}
+}
+
+fn main() {
+ MyLogger::init().unwrap();
+
+ info!("a log from `MyLogger`");
+}