Logger

Small, easy to use and extensible logger which prints beautiful logs.
Inspired by logger for Android.

Getting Started

Just create an instance of Logger and start logging:

var logger = Logger();

logger.d("Logger is working!");

Instead of a string message, you can also pass other objects like List, Map or Set.

Output

Log Console

If you are creating a Flutter app, you can use the logger_flutter extension. Shake the phone to show an on device console.

Documentation

Log level

You can log with different levels:

logger.v("Verbose log");

logger.d("Debug log");

logger.i("Info log");

logger.w("Warning log");

logger.e("Error log");

logger.wtf("What a terrible failure log");

To show only specific log levels, you can set:

Logger.level = Level.warning;

This hides all verbose, debug and info log events.

Options

When creating a logger, you can pass some options:

var logger = Logger(
  filter: null, // Use the default LogFilter (-> only log in debug mode)
  printer: PrettyPrinter(), // Use the PrettyPrinter to format and print log
  output: null, // Use the default LogOutput (-> send everything to console)
);

If you use the PrettyPrinter, there are more options:

var logger = Logger(
  printer: PrettyPrinter(
    methodCount: 2, // number of method calls to be displayed
    errorMethodCount: 8, // number of method calls if stacktrace is provided
    lineLength: 120, // width of the output
    colors: true, // Colorful log messages
    printEmojis: true, // Print an emoji for each log message
    printTime: false // Should each log print contain a timestamp
  ),
)

LogFilter

The LogFilter decides which log events should be shown and which don't.

The default implementation (DebugFilter) shows all logs with level >= Logger.level while in debug mode. In release mode all logs are omitted.

You can create your own LogFilter like this:

class MyFilter extends LogFilter {
  @override
  bool shouldLog(LogEvent event) {
    return true;
  }
}

This will show all logs even in release mode. (NOT a good idea)

LogPrinter

The LogPrinter creates and formats the output, which is then sent to the LogOutput.

You can implement your own LogPrinter. This gives you maximum flexibility.

A very basic printer could look like this:

class MyPrinter extends LogPrinter {
  @override
  void log(LogEvent event) {
    println(event.message);
  }
}

Important: Every implementation has to send its output using the println() method.

If you created a cool LogPrinter which might be helpful to others, feel free to open a pull request. :)

LogOutput

LogOutput sends the log lines to the desired destination.

The default implementation (ConsoleOutput) send every line to the system console.

class ConsoleOutput extends LogOutput {
  @override
  void output(OutputEvent event) {
    for (var line in event.lines) {
      print(line);
    }
  }
}

Possible future LogOutputs could send to a file, firebase or to Logcat. Feel free to open pull requests.

logger_flutter extension

The logger_flutter package is an extension for logger. You can add it to any Flutter app. Just shake the phone to show the console.

1. Add logger_flutter to your pubspec.yaml
2. Add the following code into your widget tree

LogConsoleOnShake(
  child: Container() // Your widgets
),

More documentation coming soon.

GitHub

https://github.com/leisim/logger