Architectural Patterns, Design Patterns, and Idioms: How Software is Structured

Software architecture is organized across three levels of abstraction: architectural patterns, design patterns, and idioms. Architectural patterns define the overall structuring principle of a system, while design patterns describe smaller units and relationships within subsystems. Idioms represent the lowest level, addressing language-specific implementation details for components and their relationships. Because idioms depend on a programming language's features, the same concept can look different across languages or may not apply at all in some. For instance, C++ relies on reference-counting idioms for memory management, whereas Smalltalk's built-in garbage collection makes such idioms unnecessary.