EPackage

EPackage is a core construct in the Eclipse Modeling Framework (EMF) used to define a namespace for a set of related meta-objects in an Ecore model. An EPackage groups classifiers such as EClass, EEnum, and EDataType, and may also contain subpackages. The package provides a namespace URI (nsURI) that uniquely identifies it across models and tools, a namespace prefix (nsPrefix) used in serialized forms, and a human-readable name.

Each EPackage holds a collection of EClassifiers via getEClassifiers(), and can reference subpackages via getESubpackages(). It also specifies an associated factory (eFactoryInstance) responsible for creating instances of the contained classifiers.

In EMF, EPackages are registered in the global EPackage.Registry by their nsURI, enabling dynamic loading and cross-model instance creation. Generated models typically expose a static singleton instance (eINSTANCE) for the package, which provides access to the meta-objects defined in the package.

EPackages play a central role in model serialization, deserialization, and code generation, serving as the backbone for defining the structure and semantics of a model. They ensure consistent identification of meta-elements across tools and runtimes, and facilitate the creation of runtime instances via the associated factory.

See also: Ecore, EClassifier, EFactory, EObject, EPackage.Registry.