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OCL evaluating derived stereotype attributes [message #1712416]

Fri, 23 October 2015 21:46

Johan Van Noten

Messages: 87
Registered: July 2009

Member

Version: Papyrus 1.1.2 Nightly (2015-10-21)

As my colleague Klaas posted before (https://www.eclipse.org/forums/index.php/t/469618/) there are some limitations as to defining the value for derived values through OCL.

As far as I saw, it doesn't cover what I tried today: use a derived value in an OCL constraint.

As an example, I used the derived "derived" attribute of a SysML Requirement.
The model shown below (and included in the attached zip) shows the problem.
Starting the interative Xtext OCL console and performing the shown OCL queries, shows that the derived "derived" attribute is oclInvalid, while the diagram correctly shows its value as "Requirement2".

index.php/fa/23689/0/

Additionally tried:
You don't have to look in any profiles to find derived values. Also UML has derived values. E.g. the "part" attribute of a Component is a derived value.
When I try to use that in an OCL query, it seems to work fine.

index.php/fa/23691/0/

Question:
* Does this mean that derived attributes of stereotypes cannot be used in OCL queries?
* As a consequence: constraints defined on profiles cannot make use of derived attributes?
* If OCL doesn't know the value, is it Papyrus that is calculated the value?

Thanks,
Johan

Attachment: 20151023 OCLDerived.png
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Attachment: 20151023 OCLInvalid.zip
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Attachment: 20151023 OCLDerived-UML.png
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Re: OCL evaluating derived stereotype attributes [message #1712427 is a reply to message #1712416]

Sat, 24 October 2015 08:45

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

The problem is that Requirement2 is a nested classifier which fails to
convert to the MOF-like OCL Pivot model that has no support for nested
classifiers. Probably just requires the nesting hierarchy to be
flattened with stylized names.

If a query mechanism is simple enough to be evaluated directly on the
UML model you see useful text.

If a more advanced internal mechanism requires conversion of the nested
classifier you get a disappointing result.

https://bugs.eclipse.org/bugs/show_bug.cgi?id=480562 raised.

Regards

Ed Willink

On 23/10/2015 22:46, Johan Van Noten wrote:
> Version: Papyrus 1.1.2 Nightly (2015-10-21)
>
> As my colleague Klaas posted before (https://www.eclipse.org/forums/index.php/t/469618/) there are some limitations as to defining the value for derived values through OCL.
>
> As far as I saw, it doesn't cover what I tried today: use a derived value in an OCL constraint.
>
> As an example, I used the derived "derived" attribute of a SysML Requirement.
> The model shown below (and included in the attached zip) shows the problem.
> Starting the interative Xtext OCL console and performing the shown OCL queries, shows that the derived "derived" attribute is oclInvalid, while the diagram correctly shows its value as "Requirement2".
>
>
>
> Additionally tried:
> You don't have to look in any profiles to find derived values. Also UML has derived values. E.g. the "part" attribute of a Component is a derived value.
> When I try to use that in an OCL query, it seems to work fine.
>
>
>
> Question:
> * Does this mean that derived attributes of stereotypes cannot be used in OCL queries?
> * As a consequence: constraints defined on profiles cannot make use of derived attributes?
> * If OCL doesn't know the value, is it Papyrus that is calculated the value?
>
> Thanks,
> Johan
>
>

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