[mdt-ocl.dev] retyping through oclAsType; clarifications

[Laurent Goubet <laurent.goubet@xxxxxxx>]

Hi all,

I need some clarifications about the actual definition of the 
"oclAsType" operation. I'll refer to some parts of the specification 
here and there; I'm refering to the 2.1 draft for this.

here are the four examples I'll base my ramblings on :

A- 3.oclAsType(Integer)
B- 3.oclAsType(Real)
C- 3.oclAsType(OclVoid)
D- 3.oclAsType(OclInvalid)

And the actual question : what are the expected results of each of 
these? I would say
A- integer "3"
B- integer "3"
C- invalid
D- invalid

Why I am confused about these?
7.4.6 tells us :
----------8<----------
      object.oclAsType(Type2) --- changes the static type of the 
expression to Type2
An object can only be re-typed to a type to which it conforms. If the 
actual type of the object, at evaluation time, is not
a subtype of the type to which it is re-typed, then the result of 
oclAsType is invalid.
Casting provides visibility, at parse time, of features not defined in 
the context of an expression's static type. It does not
coerce objects to instances of another type, nor can it provide access 
to hidden or overridden features of a type. For this,
the feature call is qualified by the name of the type (a path name, if 
necessary) whose definition of the feature is to be
accessed.
---------->8----------
Which confirms the "expected results" I gave above. Yet
7.5.9 lists :
----------8<----------
oclAsType (t : OclTypeClassifier) : instance of OclType
---------->8----------
so the result of B should be the "double" 3.0 and not the "integer" 3.
11.2.5 seems to confirm this with the post condition of oclAsType :
----------8<----------
post: (result = self) and result.oclIsTypeOf( t )
---------->8----------
Except if "oclIsTypeOf" checks the static type of its source instead of 
its actual type.

I believe that both 7.5.9 and 11.2.5 should be revisited to take into 
account the rules of 7.4.6 that were updated with OCL 2.1. Furthermore, 
7.4.6 tells us that "If the actual type of the object, at evaluation 
time, is not a subtype of the type to which it is re-typed, then the 
result of oclAsType is invalid." whereas 11.2.5 says "if the actual type 
of self at evaluation time does not conform to t, then the oclAsType 
operation evaluates to null." which makes unclear the results of both C 
and D above.

What do you think about these?

Laurent