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Query over association instead of the classes (classifiers) with OCL [message #1231452]

Tue, 14 January 2014 18:09

Hamid Qartal

Messages: 33
Registered: December 2013

Member

suppose I have a simple Ecore as bellow:

	

   ----  (0..3)          (0..*)  ---------
  | A  | ---------------------- |   B     |               // AB is association name 
   ----         AB              |-------- |
                                |age:EInt |
                                 ---------

I would like to write a query that its output is as below:

	

  ----  (0..3)          (0..*)  ---------
 | A  | ---------------------- |   B'    |                // AB' is  association name
  ----         AB'             |-------- |                // B' is subset of B where age > 20
                               |age:EInt |                // and AB' is subset of AB 
                                ---------

I can write a query to get B' like

B'=B->select(b:B | B.age>20)

I would like to write a query in OCL to get AB'. Semi-formal definition of AB' would be:

AB'=  all AB which its B side is restricted to B'

, in other words AB' is the same association as AB, but its target(co-domain) is restricted to B'.

I looked at OCL reference, but it seems that it is intended to work on Classes (like A and B here) rather than associations (like AB) in terms of query results. Am I right?

Any suggestion is appreciated.

Thanks

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Re: Query over association instead of the classes (classifiers) with OCL [message #1231458 is a reply to message #1231452]

Tue, 14 January 2014 18:22

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

You are very vague about the relationship of B and B' but it seems that
where you write query but actually you are performing a transformation.

OCL as specified cannot create objects so a query cannot help. The new
Pivot binding of Eclipse OCL has an experimental implementation of type
constructors, so you might be able to do what you want. But it doesn;'t
seem right at all.

You should use a transformation language, nearly all of which use OCL as
theuir underlying query foundation.

Regards

Ed Willink

On 14/01/2014 18:09, Hamid Qartal wrote:
> suppose I have a simple Ecore as bellow:
>
>
>
> ---- (0..3) (0..*) ---------
> | A | ---------------------- | B | // AB is
> association name ---- AB |-------- |
> |age:EInt |
> ---------
>
> I would like to write a query that its output is as below:
>
>
>
> ---- (0..3) (0..*) ---------
> | A | ---------------------- | B' | // AB' is
> association name
> ---- AB' |-------- | // B' is
> subset of B where age > 20
> |age:EInt | // and AB' is
> subset of AB ---------
>
> I can write a query to get B' like B'=B->select(b:B | B.age>20)
>
> I would like to write a query in OCL to get AB'. Semi-formal
> definition of AB' would be: AB'= all AB which its B side is
> restricted to B', in other words AB' is the same association as AB,
> but its target(co-domain) is restricted to B'.
>
>
> I looked at OCL reference, but it seems that it is intended to work on
> Classes (like A and B here) rather than associations (like AB) in
> terms of query results. Am I right?
>
> Any suggestion is appreciated.
>
> Thanks

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Re: Query over association instead of the classes (classifiers) with OCL [message #1231485 is a reply to message #1231458]

Tue, 14 January 2014 19:51

Hamid Qartal

Messages: 33
Registered: December 2013

Member

B' here is subset of B, in OO terms we can consider B' is a new Type which inherits B so:

B' extends B

http://s29.postimg.org/3w7mtmucn/Screen_Shot_2014_01_14_at_2_21_49_PM.png

Actually I don't intend to create a new type ( I know that is another story). I intend to query association. As I wrote I can write to get B':

 B'=B->select(b:B | B.age>20)

My question is that can I write a query on associations like AB-> select (ab:AB | AB->codomain()=B'). so the query returns me association instead of class.

As you see I am not questioning creation of the types and association, but just having query on associations.

Thanks

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