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.