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[QVT] result of allSubobjects on sets [message #727429]

Wed, 21 September 2011 09:33

Wilbert Alberts

Messages: 209
Registered: June 2010

Senior Member

Hi,

I'm having some troubles understanding the effect of invoking allSubobjects() on a set.

Assume that self.persons represents a set of Person.
Assume that a Person might have other references to Persons.

What is the difference between:
-1- self.persons.allSubobjects() and
-2- self.persons->allSubobjects()
when invoked in a QVT transformation?

Obviously I tried it and got
-1- [ p1, p2 ]
-2- [[ p1, p2 ]]

allSubobjects is specified as an operation that returns a Set(Element) when invoked on an Element.
However, what happens when allSubobjects is invokved on a Set(Element)?

Greetings,
Wilbert.

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Re: [QVT] result of allSubobjects on sets [message #727518 is a reply to message #727429]

Wed, 21 September 2011 13:49

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

self.persons.allSubobjects() is a shortform for
self.persons->collect(allSubobjects()) so it should evaluate to a Bag.

self.persons->allSubobjects() is wrong; raise a Bugzilla.
allSubObjects() is defined on Element and Collections do not conform to
Element; therefore a semantic error should be reported. It looks as if
the implementation just uses eContents() behind the scenes and so
creates a Set of the internal collection. Even if QVT were to define
allSubObjects(), I doubt it would be defined as Set{self} when just self
would be simpler.

Regards

Ed Willink

On 21/09/2011 10:33, Wilbert Alberts wrote:
> Hi,
>
> I'm having some troubles understanding the effect of invoking
> allSubobjects() on a set.
>
> Assume that self.persons represents a set of Person.
> Assume that a Person might have other references to Persons.
>
> What is the difference between:
> -1- self.persons.allSubobjects() and
> -2- self.persons->allSubobjects()
> when invoked in a QVT transformation?
>
> Obviously I tried it and got
> -1- [ p1, p2 ]
> -2- [[ p1, p2 ]]
>
> allSubobjects is specified as an operation that returns a Set(Element)
> when invoked on an Element.
> However, what happens when allSubobjects is invokved on a Set(Element)?
>
> Greetings,
> Wilbert.
>
>

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