ALF11 — An abstract operation should not be allowed to have a body

Specification: Action Language for Foundational UML (Alf) v1.0.1, formal/2013-09-01

Subclause: 10.5.3

In Subclause 10.5.3 Operations, under “Operation Method” it says “An abstract operation does not have a method.” However, the syntax allows an abstract operation to have a body, and there is no constraint in the abstract syntax for OperationDefinition (Subclause 15.2.16) to disallow this.

An OperationDefinition for an abstract operation should be disallowed from having a body, either in the syntax or through a static semantic check.

Add constraint preventing an abstract OperationDefinition from having a body

Agreed that an abstract OperationDefinition should not be allowed to have a body. Making this a constraint, rather than a syntax error, would be less severe, since parsing could continue even with such an error. However, the concrete syntax production should still be updated so that an abstract OperationDefinition without a body is not considered to be a stub (otherwise the MemberStub constraint would be violated for all abstract OperationDefinitions).