EClasses

EClasses are the core element of the Ecore metamodel used by the Eclipse Modeling Framework (EMF). An EClass represents a classifier in an Ecore model and defines the structure for creating instances of EObject. In a model, EClasses act as blueprints that describe the properties and behavior of objects within a domain.

An EClass can participate in inheritance through its super types, accessible via the ESuperTypes collection. This enables single inheritance between EClasses, so subclasses inherit structural features and operations from their supertypes. The features of an EClass are its structural features, which are instances of EAttribute and EReference and collectively form the EStructuralFeatures of the class. EAttributes model data values, while EReferences model links to other EObjects. References may be single-valued or multi-valued, and may be contained or non-contained, with containment indicating ownership for composition relationships. EOperations, along with their parameters, define behavior that is not directly represented by structural features.

EClasses also carry metadata such as flags for abstract and interface, which influence code generation and instantiation. An EClass with the abstract flag cannot be directly instantiated, while the interface flag affects how generated code exposes the class in Java. EClasses belong to an EPackage, which groups related classifiers and provides a namespace.

Instances of an EClass are EObjects. When an Ecore model is used to generate code, each EClass typically maps to a Java interface and an implementation class, with getters and setters created for attributes and references. EClasses can also be used at runtime in dynamic EMF applications without code generation.

Example: a Person EClass may define attributes like name (string) and birthDate (date), and a reference to an Address EClass. EClasses form the foundational structure for modeling domains within EMF.