Access Modifiers in Dart Overview#

Dart controls visibility through a simple but powerful privacy model based on library boundaries. Unlike many OOP languages, Dart uses implicit public access and explicit private access (with _ prefix) to manage encapsulation and API boundaries.

Key Concepts#

1. Public and Private Members#

• Default public visibility
• _ prefix for private members
• Applies to classes, variables, and functions

2. File-level Privacy#

• Privacy within the same library
• Multiple files in the same library
• Part-of directives

3. Cross-library Privacy#

• Private members in library exports
• Hiding implementation details
• Public-facing APIs

4. Best Practices#

• When to use private members
• Library design principles
• Documentation conventions
• Testing private members