🚀 Hot Module Replacement for Dart Applications

HMR Dart is a Hot Module Replacement system specially designed for command-line Dart applications.

It allows you to :

• Hot reload code without restarting the application
• Maintain application status during updates
• Monitor files in real time
• Intelligently manage recompilations

🛠 Key features

Feature	Description
🪄 Ready to use	No configuration required
⚡ Instant reloading	Instant code update
🎯 Targeted surveillance	Filtering by glob patterns (includes/excludes)
🔍 Visual feedback	ANSI colours + change counter
⏱️ Debounce mechanism	Delayed recompilation
🔄 Error management	Compiler error messages with highlight
📝 Extendable	Build your own HMR system using event handling
📦 Extremely small size	Package size < 10kb

Global usage

Installation

Install the package globally in your environment.

dart pub global activate hmr

Configuration

In your pubspec.yaml, you can add an additional configuration to the hmr.

hmr:
  # Change the location of the input file
  entrypoint: bin/main.dart
  
  # Delay before recompilation in milliseconds
  # If not specified, the recompilation will be immediate and you don't have any debounce
  debounce: 5
  
  # Only include files that meet the following criteria
  includes:
    - '**/*.txt'
    - '**/*.dart'
      
  # Exclude files meeting the following criteria
  excludes:
    - '.dart_tool/**'

The inclusion and exclusion of files is optional. If you don't specify any criteria, all files matching the Glob(‘**.dart’) criterion will be monitored.

Usage

$ cd /path/to/your/project
$ hmr

The Glob library is used to manage the inclusion and exclusion of monitored files.

📦 Manual installation

Add to your pubspec.yaml :

dependencies:
  hmr: ^1.0.0

🚀 Usage

Create a bin/hmr.dart file.

import 'package:hmr/hmr.dart';

void main() {  
  final runner = Runner(
    tempDirectory: Directory.systemTemp,
    entrypoint: File(
      path.join([
        Directory.current.path,
        'bin',
        'main.dart'
      ])
    ));

  final watcher = Watcher(
    onStart: () => print('Watching for changes...'),
    middlewares: [
      IgnoreMiddleware(['~', '.dart_tool', '.git', '.idea', '.vscode']),
      DebounceMiddleware(Duration(milliseconds: 5), dateTime),
      IncludeMiddleware([Glob("**.dart")]),
    ],
    onFileChange: (int eventType, File file) async {
      final action = switch (eventType) {
        FileSystemEvent.create => 'created',
        FileSystemEvent.modify => 'modified',
        FileSystemEvent.delete => 'deleted',
        FileSystemEvent.move => 'moved',
        _ => 'changed'
      };
      
      print('File $action ${file.path}');
      await runner.reload();
    });

  watcher.watch();
  runner.run();
}

Start HMR mode:

$ dart run bin/hmr.dart