fimber_io 0.4.2

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fimber_io #

Extensible logging for Flutter. Dart::IO version with File loggers.

Package is based on famous Android logging library API - Timber, this is library for simplify logging for Flutter. Using similar (as far as Dart lang allows) method API with same concepts for tree and planting logging tree. Also check out flutter_fimber which extends fimber to platform specific output and logging style.

Getting Started #

To start add using it:

Add fimber_io to pubspec.yaml #

  fimber_io: ^0.4.2
  • remember about import in file you plan to use Fimber
import 'package:fimber_io/fimber_io.dart';

Initialize logging tree on start of your application #

void main() {
  // app code here ...
  // DebugTree options for time elapsed
  // by default DebugTree will output timestamp of the VM/Flutter app
  // to enable elapsed time since planting the tree log

Start using it with static methods: #

import 'fimber.dart';

void main() {
  var parameter = 343.0;
  // use directly
  Fimber.i("Test message $argument");
  Fimber.i("Extra error message", ex: Exception("Test thorwable"));
  // other log levels
  try {
    throw Exception("Exception thrown");
  } catch (e, stacktrace) {
    // providing `stacktrace` will better show where issue was thrown
    // if not provided will use log line location.
    Fimber.i("Error caught.", ex: e, stacktrace: stacktrace);

This will log the value and grab a TAG from stacktrace - that is little costly and if more logs will be done per second.

Colorize logs - ColorizeStyle #

useColors property set to true will use default colors of the logos, you can change the mapping with in colorizeMap for DebugTree and CustomFormatTree The useColors by default is disabled.

ColorizeStyle Aggregates list of AnsiStyle so you can combine styles together.

AnsiStyle is combination of AnsiColor and AnsiSelection values

Here is output of test output.

Colorize Test Output

Create tagged version of Fimber #

And use its instance inside class, you can create logger for a dart file or for a class.

var logger = FimberLog("MY_TAG");

void main() {
  logger.d("Test message");

// or inside a class
class SomeBloc {
  var logger = FimberLog("SomeBloc");
  String fetchMessage() {
    logger.d("About to fetch some data.");
    var data = "load something";

    logger.d("Retrived data (len = ${data.length}");
    return data;

Use block function and pass method that uses logger. #

Use this function to log multiple messages with same tag, allows optional return value. Due to nature of auto-tag generation from stacktrace this block only does it once and create local FimberLog instance to pass into the anonymous method.

    var someMessage = "Test message from inside of block";
    var output = Fimber.block((log) {
      log.d("Started block");
      var i = 0;
      for (i = 0; i < 10; i++) {
        log.d("$someMessage, value: $i");
      log.i("End of block");
      return i;

Custom line formatters #

Use custom line formatters to define your logging format.

        logFormat: "${CustomFormatTree.TIME_ELAPSED_TOKEN} ${CustomFormatTree
            .MESSAGE_TOKEN} ${CustomFormatTree.TIME_STAMP_TOKEN}"

Use file log tree - the logs will go to a log file (Useful in DartVM apps). There are log rolling with size and time/date interval, so it is possible to setup log output per hour/day or any other time.

see: SizeRollingFileTree or TimedRollingFileTree or use abstract class RollingFileTree to create your own version of rolling log file.

TODO - road map #

Licence #

   Copyright 2018 Mateusz Perlak

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   See the License for the specific language governing permissions and
   limitations under the License.

[0.4.2] - Fixed versioning #

  • fixed versioning

[0.4.1] - Bug fixes #

  • #75 issue - Fix for TimedRollingFileTree missing passed logLevels and logFormat
  • #73 issue - Fix for mute levels list not being distinct

0.4.0 Fimber dependency on dart::io separated #

  • moved all File based and dart::io package dependent code from fimber to fimber_io

0.3.3 fimber_io split from fimber package #


import 'package:fimber_io/fimber_io.dart';

void main() {
  // todo example with files.

  Fimber.i("Test log");
  Fimber.d("Test DEBUG");

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  fimber_io: ^0.4.2

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:fimber_io/fimber_io.dart';
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Learn more about scoring.

We analyzed this package on Jul 10, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.8.4
  • pana: 0.13.14

Analysis suggestions

Package not compatible with runtime flutter-web on web


  • package:fimber_io/fimber_io.dart that imports:
  • package:fimber_io/src/file_log.dart that imports:
  • dart:io

Package not compatible with runtime js


  • package:fimber_io/fimber_io.dart that imports:
  • package:fimber_io/src/file_log.dart that imports:
  • dart:io

Health suggestions

Fix lib/src/file_log.dart. (-0.50 points)

Analysis of lib/src/file_log.dart reported 1 hint:

line 47 col 7: Future results in async function bodies must be awaited or marked unawaited using package:pedantic.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.7.0 <3.0.0
fimber ^0.4.2 0.4.2
Dev dependencies
pedantic ^1.8.0
test ^1.6.0