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  1. OMG Issue

UML24 — Meaning of BodyCondition and its alignment with OCL

  • Key: UML24-51
  • Legacy Issue Number: 15259
  • Status: closed  
  • Source: NASA ( Maged Elaasar)
  • Summary:

    The UML superstructure allows an Operation to have:

    bodyCondition: Constraint[0..1] : An optional Constraint on the result values of an invocation of this Operation. Subsets Namespace::ownedRule

    Since bodyCondition is of type Constraint, its expression must be boolean according to clause 7.3.10 (Constraint):

    [1] The value specification for a constraint must evaluate to a Boolean value.

    Now, the OCL spec states in 7.3.6 that an operation body expression has the form:

    context Typename::operationName(param1 : Type1, ... ): ReturnType
    body: – some expression

    and gives an example:

    context Person::getCurrentSpouse() : Person
    pre: self.isMarried = true
    body: self.mariages->select( m | m.ended = false ).spouse

    Notice that in this example, the expression is NOT boolean, therefore if "self.mariages->select( m | m.ended = false ).spouse" was used as an expression in the bodyCondition, it would not be valid.

    Am I missing something?

    in RSA, we got around this by requiring the expression to be of the format:

    context Typename::operationName(param1 : Type1, ... ): ReturnType
    body: result = some expression

    Is the keyword "result" legal in the expression of bodyCondition?

  • Reported: UML 2.3 — Wed, 19 May 2010 04:00 GMT
  • Disposition: Resolved — UML 2.4
  • Disposition Summary:

    OCL body expressions and UML bodyConditions are inconsistently specified. For the UML spec, the
    bodyConditions need to be Boolean. The way we do this is by naming the result parameter of all of the
    operations as “result”. Then the body expressions should be of the form “result = <expression>”.
    Unfortunately, doing this in RSA causes type errors because RSA gives a well-typed expression its internal
    Boolean type which is not the same type as the UML 2.5 PrimitiveType Boolean.
    So in order to keep RSA as happy as possible, and reduce error-prone work, we’ll keep the body expressions
    in the metamodel in the OCL-like form (without the “result =”) and cause the XMI generation process to
    wrap result = (. . . ) around all of the body expressions.
    This also resolves 13258.

  • Updated: Fri, 6 Mar 2015 20:58 GMT