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  1. OMG Issue

SYSML2 — Connection declaration does not allow a feature value

Open Closed All
  • Key: SYSML2-84
  • Status: open  
  • Source: Model Driven Solutions ( Mr. Ed Seidewitz)
  • Summary:

    The second line of the following does not parse:

    abstract connection c1;
abstract connection c2 = c3; // Error: No viable alternative at input '='

    The reason for this is that the ConnectionUsage production uses UsageDeclaration (see subclause 8.2.2.13.1):

    ConnectionUsage =
    OccurrenceUsagePrefix
    ( 'connection' UsageDeclaration
      ( 'connect' ConnectorPart )?
    | 'connect' ConnectorPart )
    UsageBody

    However, UsageDeclaration does not include ValuePart, which provides the syntax for feature values (see 8.2.2.6.2):

    Usage =
    UsageDeclaration UsageCompletion
UsageDeclaration : Usage =
    Identification FeatureSpecializationPart?
UsageCompletion : Usage =
    ValuePart? UsageBody

    On the other hand, 7.13.2 states that “A connection definition or usage (that is not of a more specialized kind) is declared as a kind of occurrence definition or usage (see 7.9.2), using the kind keyword connection”, and an occurrence declaration (in the informal sense) can, in general, include a feature value, so it would be expected to be allowable for a connection, too.

    Note that this is also a problem for interactions, but not for messages or flow connections, which explicitly allow a ValuePart (see 8.2.2.13.4):

    MessageDeclaration : FlowConnectionUsage =
      UsageDeclaration ValuePart?
      ( 'of' ownedRelationship += ItemFeatureMember )?
      ( 'from' ownedRelationship += MessageEventMember
        'to' ownedRelationship += MessageEventMember
      )?
    | ownedRelationship += MessageEventMember 'to'
      ownedRelationship += MessageEventMember

FlowConnectionDeclaration : FlowConnectionUsage =
      UsageDeclaration ValuePart?
      ( 'of'  ownedRelationship += FlowPayloadFeatureMember )?
      ( 'from' ownedRelationship += FlowEndMember
        'to'   ownedRelationship += FlowEndMember )?
    | ownedRelationship += FlowEndMember 'to'
      ownedRelationship += FlowEndMember
  • Reported: SysML 2.0a1 — Thu, 27 Apr 2023 21:30 GMT
  • Updated: Mon, 8 Apr 2024 18:21 GMT