move to test pkg
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tree: 128644c0f3c7e998106407f24ce1d23e9772888d
  1. .gitignore
  2. .status
  3. AUTHORS
  4. CHANGELOG.md
  5. LICENSE
  6. PATENTS
  7. README.md
  8. codereview.settings
  9. lib/
  10. pubspec.yaml
  11. test/
README.md

Initializing

By default, the logging package does not do anything useful with the log messages. You must configure the logging level and add a handler for the log messages.

Here is a simple logging configuration that logs all messages via print.

Logger.root.level = Level.ALL;
Logger.root.onRecord.listen((LogRecord rec) {
  print('${rec.level.name}: ${rec.time}: ${rec.message}');
});

First, set the root [Level]. All messages at or above the level are sent to the [onRecord] stream.

Then, listen on the [onRecord] stream for [LogRecord] events. The [LogRecord] class has various properties for the message, error, logger name, and more.

Logging messages

Create a [Logger] with a unique name to easily identify the source of the log messages.

final Logger log = new Logger('MyClassName');

Here is an example of logging a debug message and an error:

var future = doSomethingAsync().then((result) {
  log.fine('Got the result: $result');
  processResult(result);
}).catchError((e, stackTrace) => log.severe('Oh noes!', e, stackTrace));

When logging more complex messages, you can pass a closure instead that will be evaluated only if the message is actually logged:

log.fine(() => [1, 2, 3, 4, 5].map((e) => e * 4).join("-"));

See the [Logger] class for the different logging methods.