Issue 14986: OCL 2.1 Feature Overloading Semantics are not defined (ocl2-rtf)
Source: Model Driven Solutions (Dr. Edward Willink, ed(at)willink.me.uk)
Nature: Uncategorized Issue
Severity: 
Summary: OCL supports feature overloading and attempts to comply with UML. OCL does not define feature overloading itself. UML leaves feature overloading as a semantic variation point.


The OCL behaviour is therefore undefined. However a variety of behaviours particularly those involving null and invalid only make sense if operations are selected at run-time according to the dynamic type.


The example from an earilier pending issue:


Sequence(OclAny){3, 3.0, '3'}->count(-(-3)) = 2


wherein


UnlimitedNatural 3 widens to Integer 3 for successful comparison with Integer 3
Real 3.0 is successfully compared to Integer 3 widened to Real
String '3' widens to OclAny and fails to compare to Integer 3 widened to OclAny.


is difficult to realise if static type resolution is applicable in which case all pair-wise value comparisons would use OclAny::= rather than Real::=.


Suggest:


OCL define that features are selected dynamically at run-time.


Resolution: 
Revised Text: 
Actions taken:
January 18, 2010: received issue
Discussion: 

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Date: Mon, 18 Jan 2010 18:12:10 +0000
From: Ed Willink <ed@willink.me.uk>
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To: issues@omg.org
Subject: OCL 2.1 Feature Overloading Semantics are not defined
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Hi


OCL supports feature overloading and attempts to comply with UML. OCL does not define feature overloading itself. UML leaves feature overloading as a semantic variation point.


The OCL behaviour is therefore undefined. However a variety of behaviours particularly those involving null and invalid only make sense if operations are selected at run-time according to the dynamic type.


The example from an earilier pending issue:


Sequence(OclAny){3, 3.0, '3'}->count(-(-3)) = 2


wherein


UnlimitedNatural 3 widens to Integer 3 for successful comparison with Integer 3
Real 3.0 is successfully compared to Integer 3 widened to Real
String '3' widens to OclAny and fails to compare to Integer 3 widened to OclAny.


is difficult to realise if static type resolution is applicable in which case all pair-wise value comparisons would use OclAny::= rather than Real::=.


Suggest:


OCL define that features are selected dynamically at run-time.


    Regards


        Ed Willink