Classescollections

Classescollections is a software design concept describing a data structure or framework component that pairs class metadata with a runtime collection of objects of that class. It treats types as first‑class keys and groups instances by their declared class, enabling dynamic discovery, filtering, and manipulation of objects based on their type without relying solely on inheritance hierarchies.

In typical implementations, a central registry holds descriptors for each class, including name, fields, methods, and serializable metadata. Each descriptor is associated with a collection that stores instances of that class. The combined structure supports operations such as registering new classes, creating instances, enumerating all instances of a given type, and serializing or deserializing the stored objects. This arrangement can also facilitate reflection, type-based queries, and runtime metainformation access.

Use cases include plugin systems and component architectures where types are discovered at runtime; object-relational mappers may map records to their class types; test frameworks can generate and track objects by type; and scripting environments can expose collections of native types to scripts. Implementation considerations include leveraging language features such as reflection or runtime type information to ease development, while also addressing memory overhead, type safety, thread safety, and potential performance costs from indirection.

Variants exist, such as combining with generics for stronger compile-time type safety or using alternative keys (for example string identifiers) to support cross-language interoperability. See also reflection, registry pattern, type erasure, and generics.