Class (programming)

// Target: computer-science.bigb

An operation used when creating and initializing a software class instance. Construction should establish the representation invariant before ordinary clients can access the software object. Class inheritance and initialization order require care if construction invokes overridable object methods before subclass fields are initialized.

An abstract class cannot be instantiated directly and may combine concrete state or behavior with abstract operations that subclasses implement. Concrete object methods can depend on a representation convention that every subclass must maintain. An abstract declaration still has a result type: omitted result types in Scala 2 procedure syntax mean Unit, not an unspecified Boolean query.