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Creating objects with multi-valued children [message #483529]

Tue, 01 September 2009 21:33

Doug Bercot

Messages: 5
Registered: July 2009

Junior Member

... sorry in advance for cross-posting, but I'm a complete noob. I also
posted this query in eclipse.modeling.mdt.

If I were to create a simple object that has a containment association
with an N..N value (as shown in the "simple" model below), is there a
proper place in which I can modify the generated code such that the
contained objects are always of the correct number?

In this example, could I modify one of the factories such that a "Car"
object is always created with 4 "Tire" child objects?

TIA

<?xml version="1.0" encoding="UTF-8"?>
<ecore:EPackage xmi:version="2.0"
xmlns:xmi="http://www.omg.org/XMI";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xmlns:ecore="http://www.eclipse.org/emf/2002/Ecore"; name="simple"
nsURI="http://nunjobiznezz.com/emf/simple"; nsPrefix="simple">
<eClassifiers xsi:type="ecore:EClass" name="Car">
<eStructuralFeatures xsi:type="ecore:EReference" name="tires"
lowerBound="4" upperBound="4"
eType="#//Tires" containment="true"/>
</eClassifiers>
<eClassifiers xsi:type="ecore:EClass" name="Tires"/>
</ecore:EPackage>

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Re: Creating objects with multi-valued children [message #483674 is a reply to message #483529]

Wed, 02 September 2009 14:31

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

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Doug,

Please use the EMF newsgroup for basic EMF questions like this:

news://new.eclipse.org/eclipse.tools.emf

More comments below.

Doug Bercot wrote:
> .. sorry in advance for cross-posting, but I'm a complete noob. I also
> posted this query in eclipse.modeling.mdt.
>
> If I were to create a simple object that has a containment association
> with an N..N value (as shown in the "simple" model below), is there a
> proper place in which I can modify the generated code such that the
> contained objects are always of the correct number?
No.
>
> In this example, could I modify one of the factories such that a "Car"
> object is always created with 4 "Tire" child objects?
No, that's a bad idea, because when the deserializer creates a new Car
and then deserializes the Tires (it's generally a bad idea to given an
EClass a plural name), the Car will end up with 8 wheels instead of 4.
The Copier will have the same problem.

You could add an additional factory method (by hand) that creates Tires,
but don't change the default ones because the framework requires bare
uninitialized objects to be created.
>
> TIA
>
>
> <?xml version="1.0" encoding="UTF-8"?>
> <ecore:EPackage xmi:version="2.0"
> xmlns:xmi="http://www.omg.org/XMI";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
> xmlns:ecore="http://www.eclipse.org/emf/2002/Ecore"; name="simple"
> nsURI="http://nunjobiznezz.com/emf/simple"; nsPrefix="simple">
> <eClassifiers xsi:type="ecore:EClass" name="Car">
> <eStructuralFeatures xsi:type="ecore:EReference" name="tires"
> lowerBound="4" upperBound="4"
> eType="#//Tires" containment="true"/>
> </eClassifiers>
> <eClassifiers xsi:type="ecore:EClass" name="Tires"/>
> </ecore:EPackage>
>
>

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Doug, 
 
Please use the EMF newsgroup for basic EMF questions like this: 
<blockquote><a href="news://new.eclipse.org/eclipse.tools.emf">news://new.eclipse.org/eclipse.tools.emf</a> 
</blockquote>
More comments below. 
 
Doug Bercot wrote:
<blockquote
cite="mid:b5676bb5c31a3ca16783d165c89294b4$1@www.eclipse.org"
type="cite">.. sorry in advance for cross-posting, but I'm a complete
noob. I also posted this query in eclipse.modeling.mdt.
 
 
If I were to create a simple object that has a containment association
with an N..N value (as shown in the "simple" model below), is there a
proper place in which I can modify the generated code such that the
contained objects are always of the correct number?
 
</blockquote>
No. 
<blockquote
cite="mid:b5676bb5c31a3ca16783d165c89294b4$1@www.eclipse.org"
type="cite"> 
In this example, could I modify one of the factories such that a "Car"
object is always created with 4 "Tire" child objects?
 
</blockquote>
No, that's a bad idea, because when the deserializer creates a new Car
and then deserializes the Tires (it's generally a bad idea to given an
EClass a plural name), the Car will end up with 8 wheels instead of 4.

Ed Merks
Professional Support: https://www.macromodeling.com/

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