Paraclasses

Paraclasses are a concept in object-oriented programming that extends the idea of classes by allowing a class to have an associated "paraclass" which governs the behavior of the class itself rather than its instances. In essence, a metaclass is a class whose instances are themselves classes, and a paraclass is a specific type of metaclass. The term "paraclass" is most notably used in the Dylan programming language.

In languages that support paraclasses, the paraclass defines properties and methods that apply to the class object as a whole. This can include how the class is constructed, how it handles meta-level operations, or how it interacts with other classes. For example, a paraclass might define how new instances of its associated class are created or how class-level attributes are managed.

This contrasts with traditional class-based object-oriented programming where methods and attributes defined in a class are typically associated with the instances of that class. Paraclasses, therefore, offer a way to modify and extend the behavior of the class definition itself, providing a more powerful and flexible meta-programming capability. The implementation and usage of paraclasses can vary significantly between programming languages that adopt the concept.