Annotation Type Ensures


  • @Retention(RUNTIME)
    @Target({CONSTRUCTOR,METHOD})
    @Incubating
    @Postcondition
    @AnnotationProcessorImplementation(EnsuresAnnotationProcessor.class)
    public @interface Ensures

    Represents a method postcondition.

    A postcondition is a condition that is guaranteed to be fulfilled by suppliers.

    A method's postcondition is executed after a method call has finished. A successor's postcondition strengthens the postcondition of its parent class, e.g. if A.someMethod declares a postcondition and B.someMethod overrides the method the postconditions are combined with a boolean AND.

    Compared to pre-conditions, postcondition annotation closures are optionally called with two additional closure arguments: result and old.

    result is available if the corresponding method has a non-void return-type and holds the result of the method call. Be aware that modifying the internal state of a reference type can lead to side-effects. Groovy-contracts does not keep track of any sort of modifications, neither any conversion to immutability.

    old is available in every postcondition. It is a Map which holds the values of value types and Cloneable types before the method has been executed.

    Examples:

    Accessing the result closure parameter:

       @Ensures({ result -> result != argument1 })
       def T someOperation(def argument1, def argument2)  {
         ...
       }
     

    Accessing the old closure parameter:

       @Ensures({ old -> old.counter + 1 == counter })
       def T someOperation(def argument1, def argument2)  {
         ...
       }
     

    • Required Element Summary

      Required Elements 
      Modifier and Type Required Element Description
      Class value  
    • Element Detail