Package typequals.prototype.qual

Annotation Type Prototype

@Target({TYPE_USE,TYPE_PARAMETER})
@SubtypeOf({})
public @interface Prototype

The Prototype and NonPrototype qualifiers apply only to Invariant (and its subclasses). A prototype invariant is one that is not instantiated over a particular set of variables, will never be applied to values, etc. A prototype can have any operation performed on it that does not depend on properties of instance fields, and the prototype's Invariant.ppt field is null. Prototypes are often used as factory objects from which to instantiate non-prototypes, but can be used for other purposes as well.

The Prototype qualifier means an invariant that is either a prototype or not. There is not a way to say that a particular reference is definitely a prototype. A method that can be called on a prototype does not access instance fields. It cannot be a static method for two reasons:

• The method does access the swap field in some classes. This is a design flaw; the classes that currently use a swap field should probably be rewritten to be two distinct classes. (Currently, some of Daikon's invariants use the swap field approach and some use the approach of multiple classes. Making the codebase uniform would be another benefit.)
• Static method cannot override one another, so the methods need to be instance methods regardless.