Advanced Record Usage

Advanced Record Usage

About

• Performance Characteristics: Stack vs heap allocation
• JSON Serialization: Conversion patterns
• API Design: When to use records vs classes
• Limitations: Type system considerations

Main Topics

1. Memory Efficiency

   • Definition: Stack allocation benefits
   • Example:

     // Small records may be stack-allocated:
     var point = (x: 1.0, y: 2.0); // Likely on stack

2. JSON Conversion

   • Definition: Working with JSON data
   • Example:

     (String, int) fromJson(Map<String,dynamic> json) {
       return (json['name'], json['age']);
     }

3. API Design

   • Definition: Choosing records vs classes
   • Example:

     // Use records for:
     // - Temporary groupings
     // - Multiple returns
     // Use classes for:
     // - Persistent data
     // - Complex behavior

4. Type Limitations

   • Definition: Type system constraints
   • Example:

     // Cannot implement interfaces
     // Cannot extend
     // No methods (except toString/==)

5. Collection Integration

   • Definition: Using records in collections
   • Example:

     var points = [(1,2), (3,4), (5,6)];
     var namedPoints = [(x:1,y:2), (x:3,y:4)];

How to Use

• Performance: Prefer for small, short-lived data
• Serialization: Convert to/from other formats
• APIs: Document record types clearly
• Evolution: Start with records, refactor to classes if needed

How It Works

1. Compilation: Treated as value types
2. Interop: Works with existing Dart code
3. Reflection: Limited runtime introspection
4. Evolution: May gain features in future Dart versions

Example:

// API that returns a record
({String id, DateTime modified}) getFileInfo(File file) {
  return (id: file.path, modified: file.lastModifiedSync());
}

// Process collection of records
void printFiles(List<({String id, DateTime modified})> files) {
  for (var (:id, :modified) in files) {
    print('$id was modified at $modified');
  }
}

Conclusion

Advanced record usage requires understanding their performance characteristics, serialization patterns, and appropriate use cases in API design. While records excel at temporary data handling and multiple returns, traditional classes remain better suited for complex domain models and persistent data structures. Judicious use of records can lead to cleaner, more efficient Dart code.