comon_logger 0.1.2

A modular, extensible logging library for Dart. Core package with zero dependencies.

comon_logger

Zero-dependency logging core for Dart with hierarchical loggers, typed tags, filters, handlers, and extensible formatter add-ons.

Features

• Hierarchical Logger instances with propagation to Logger.root
• Structured tags with LogLevel, LogLayer, LogType, and feature
• Per-handler filtering via LogFilter
• Console, file, and custom handler support
• PrettyLogFormatter and SimpleLogFormatter out of the box
• Formatter add-ons via ConsoleLogHandler(formatters: [...])

Installation

dart pub add comon_logger

Quick Start

import 'package:comon_logger/comon_logger.dart';

void main() {
  Logger.root.addHandler(ConsoleLogHandler(
    filter: const LevelLogFilter(LogLevel.INFO),
  ));

  final log = Logger('my_app.catalog');

  log.info(
    'Products loaded: 42 items',
    layer: LogLayer.data,
    type: LogType.network,
    feature: 'catalog',
  );

  log.severe(
    'Failed to load products',
    error: Exception('Network timeout'),
    stackTrace: StackTrace.current,
    layer: LogLayer.data,
    type: LogType.network,
    feature: 'catalog',
  );
}

Configuration

Logger hierarchy

Logger('dio.request') -> Logger('dio') -> Logger.root

Handlers on Logger.root receive records from all child loggers.

Tags

Tag	Purpose	Examples
LogLevel	Severity	INFO, WARNING, SEVERE
LogLayer	Architectural origin	data, domain, widgets, app, infra
LogType	Action category	network, navigation, database, ui
feature	Free-form feature marker	catalog, auth, checkout

Filters

const filter = CompositeLogFilter([
  LevelLogFilter(LogLevel.INFO),
  TypeLogFilter({LogType.network}),
], mode: CompositeMode.and);

Formatter add-ons

ConsoleLogHandler can try specialized formatters first and fall back to a default formatter for all other records.

Logger.root.addHandler(ConsoleLogHandler(
  formatters: const [
    MySpecialFormatter(),
  ],
  formatter: PrettyLogFormatter(),
));

The first formatter whose canFormat(record) returns true wins.

Included formatters

Formatter	Purpose
PrettyLogFormatter	Multi-line console output with ANSI colors and emoji
SimpleLogFormatter	Compact single-line text format

Related packages

Package	Adds
comon_logger_flutter	In-app log viewer and HistoryLogHandler
comon_logger_dio	Dio interceptor and HTTP console formatter
comon_logger_dio_flutter	Rich HTTP UI renderer for Flutter logs
comon_logger_navigation_flutter	Navigation observer with structured route logs
comon_logger_share_flutter	Share/export action for the viewer
comon_logger_file	Rotating file log handler