Custom Libraries

Custom Libraries

About

  • Code Organization: Logical grouping
  • Privacy Control: Hide implementation
  • Reusability: Share across projects
  • Structure: Multiple files

Main Topics

  1. Library Declaration

    • Definition: library keyword
    • Example:
      library my_awesome_library;
  2. Part Files

    • Definition: Split implementation
    • Example:
      part 'src/implementation.dart';
      part 'src/helpers.dart';
  3. Export Directives

    • Definition: Public API
    • Example:
      export 'src/public.dart';
      export 'src/types.dart';
  4. Private Implementation

    • Definition: src/ directory
    • Example:
      lib/
        my_library.dart
        src/
          implementation.dart
  5. Documentation

    • Definition: API docs
    • Example:
      /// A utility library for string operations
      library string_utils;

How to Use

  • Structure: Logical modules
  • Privacy: Hide implementation
  • Documentation: Explain purpose
  • Testing: Test public API

How It Works

  1. Scope: Library boundary
  2. Privacy: _ prefix
  3. Composition: Parts form one library
  4. Distribution: Via packages

Example:

// lib/weather.dart
library weather;

export 'src/models.dart';
export 'src/api.dart';
export 'src/exceptions.dart';

// Implementation files in src/

Conclusion

Custom libraries in Dart enable clean code organization through logical grouping and controlled visibility. By using library declarations, part files, and export directives, developers can create well-structured, maintainable codebases with clear public APIs.