Classswitch

Classswitch, sometimes written as class switch or class-switch, is a term used in software development to describe mechanisms that select behavior or presentation based on an object's class. The concept appears in several related contexts, including runtime type dispatch in object-oriented programming and user interface styling in web development.

In programming, a class switch refers to code that branches execution depending on an object's runtime class. This is often implemented with explicit type checks or a switch statement on a type tag and can lead to brittle, hard-to-maintain code when new classes are added. To mitigate this, developers commonly use polymorphism through virtual methods, the visitor pattern, or double dispatch, which aim to decouple type inspection from behavior selection. In languages with discriminated unions, a switch on the union’s tag can perform type narrowing and activate appropriate logic without direct class checks.

In user interface development, class switching describes the practice of changing an element’s appearance or state by adding or removing CSS classes. This approach enables dynamic styling and interactivity, such as toggling an active state, showing or hiding sections, or applying themes. Practical tools include DOM APIs like classList, which provide convenient methods to toggle, add, or remove classes in response to user actions or data changes.

Related terms and variants include class-switching patterns in design and architecture discussions. While the term is informal and its precise meaning depends on context, it generally concerns mechanisms for selecting behavior or presentation based on class information, either at runtime in code or at the level of user interface styling.