commit | 1bc0c8a2b72d3fce06d835f515f3108a74230f3c | [log] [tgz] |
---|---|---|
author | Olivier Chafik <olivier.chafik@gmail.com> | Wed Jul 01 16:08:15 2015 +0100 |
committer | Olivier Chafik <olivier.chafik@gmail.com> | Wed Jul 01 16:08:15 2015 +0100 |
tree | 7e21ea292c8547bc58d78be4551de62974b5b6a2 | |
parent | 8a8a3d34f7d02e28919940ffc6a8e8e21b5023b0 [diff] |
Improve Logger.root (static final instead of getter that looks the cached instance up through the factory constructor) (note: static fields are lazy anyway)
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.
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.