comon_logger 0.1.0

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

comon_logger

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

Features

• Hierarchical loggers — Logger('dio.request') is a child of Logger('dio'), which is a child of Logger.root
• Typed tags — LogLevel, LogLayer, LogType, feature for granular filtering
• Pluggable handlers — attach any number of handlers to any logger
• Pluggable filters — each handler has its own filter chain
• Pluggable formatters — pretty (ANSI + emoji) or simple (single-line) output
• Extensible — create custom layers, types, filters, formatters, and handlers
• Zero dependencies — pure Dart, works everywhere

Quick Start

import 'package:comon_logger/comon_logger.dart';

void main() {
  // Add a handler to root — it receives ALL logs from every logger
  Logger.root.addHandler(ConsoleLogHandler(
    filter: LevelLogFilter(LogLevel.FINE),
  ));

  // Create a named logger
  final log = Logger('my_app.catalog');

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

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

Architecture

Actors (produce logs)                    Handlers (consume logs)
┌─────────────────────┐                  ┌──────────────────────────────────┐
│ DioInterceptor      │──log──┐          │ LogFilter → ConsoleLogHandler   │
│ NavigatorObserver    │──log──┤          │ LogFilter → FileLogHandler      │
│ BlocObserver        │──log──┼──► Logger.root ──► handlers ──┤            │
│ Any code            │──log──┘          │ LogFilter → HistoryLogHandler   │
└─────────────────────┘                  │ LogFilter → AnalyticsLogHandler │
                                         └──────────────────────────────────┘

Logger Hierarchy

Loggers form a dotted-name hierarchy. Records propagate up from child to parent:

Logger('dio.request')  →  Logger('dio')  →  Logger.root ('')

Handlers on Logger.root receive records from all loggers. Handlers on Logger('dio') receive records from Logger('dio') and Logger('dio.request').

Log Levels

Level	Value	Description
FINEST	300	Most verbose
FINER	400	Verbose
FINE	500	Fine-grained
CONFIG	700	Configuration info
INFO	800	Informational
WARNING	900	Potential problem
SEVERE	1000	Serious failure
SHOUT	1200	Critical / fatal
OFF	2000	Disables logging

Tags

Each LogRecord can carry typed tags for filtering:

• LogLayer — architectural layer: data, domain, widgets, app, infra
• LogType — action type: network, database, navigation, logic, ui, lifecycle, analytics, performance, security, general
• feature — free-form string (e.g. 'catalog', 'auth')

Custom Tags

// Simple constants
const kPaymentsLayer = LogLayer('payments');
const kDeeplinkType = LogType('deeplink');

// Register for UI filter visibility
LogLayer.register(kPaymentsLayer);
LogType.register(kDeeplinkType);

Filters

// By level
const filter = LevelLogFilter(LogLevel.WARNING);

// By type
const filter = TypeLogFilter({LogType.network, LogType.database});

// By layer
const filter = LayerLogFilter({LogLayer.data});

// By feature
const filter = FeatureLogFilter({'catalog', 'auth'});

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

Formatters

• PrettyLogFormatter — multi-line with ANSI colors and emoji
• SimpleLogFormatter — compact single-line format

Related Packages

Package	Description
comon_logger_flutter	Flutter UI log viewer + HistoryLogHandler
comon_logger_dio	Dio HTTP interceptor
comon_logger_dio_flutter	Beautiful HTTP log renderer for Dio
comon_logger_navigation_flutter	NavigatorObserver + navigation log renderer
comon_logger_share_flutter	Share/export toolbar action
comon_logger_file	File-based log handler with rotation
comon_logger_devtools_extension	DevTools browser extension