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EMF and final filed initialization [message #478910]

Fri, 07 August 2009 13:00

Manuel Selva

Messages: 189
Registered: July 2009
Location: Grenoble, France

Senior Member

Hi all,

I am modeling a class with two final (regarding Java) fields, i.e two fields that can't be modified after object's creation.

I saw a changeable attribute in EMF code generator allowing me to not generate setter for these fields.
It works but i am not able to set these fields ....

How should I work witn non changeable fields ? Can you point me to the documention about that ?

Thanks in advance

Manu

http://manuelselva.wordpress.com/

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Re: EMF and final filed initialization [message #478915 is a reply to message #478910]

Fri, 07 August 2009 13:18

Ed Merks

Messages: 30693
Registered: July 2009

Senior Member

Manuel,

Comments below.

Manuel Selva wrote:
> Hi all,
>
> I am modeling a class with two final (regarding Java) fields, i.e two
> fields that can't be modified after object's creation.
Not with Ecore you won't. :-P
>
> I saw a changeable attribute in EMF code generator allowing me to not
> generate setter for these fields. It works but i am not able to set
> these fields ....
>
> How should I work witn non changeable fields ? Can you point me to the
> documention about that ?
Typically these are things that will be derived or computed in some way.

You should keep in mind that deserialization involves creating an
object, and then later setting the values of fields. The copier does
this as well. So this notion of something being final after
construction (after the constructor completes) simply doesn't fit with
the other things the framework needs to be able to do. Probably you
need to modify your strategy...
>
> Thanks in advance
>
> Manu

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Re: EMF and final filed initialization [message #478917 is a reply to message #478915]

Fri, 07 August 2009 13:50

Manuel Selva

Messages: 189
Registered: July 2009
Location: Grenoble, France

Senior Member

Hi Ed,

Once again, thanks for your quick and clear answer.

I guess I will not set the changeable attribute to false and carefully ALWAYS set this two ("final") attributes after creating them using the generated factory.

Is it the "right" way to do ?

Note: I was reviewing some part of my code after reading the excellent "Effective Java" book and was trying to apply it. Here it concerns the item 15 "Minimize mutability" but it seems, as you said, this item is not compatible with EMF framewrok.

Regards,

Manu

http://manuelselva.wordpress.com/

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Re: EMF and final filed initialization [message #478933 is a reply to message #478917]

Fri, 07 August 2009 14:37

Ed Merks

Messages: 30693
Registered: July 2009

Senior Member

Manu,

Comments below.

Manuel Selva wrote:
> Hi Ed,
>
> Once again, thanks for your quick and clear answer.
>
> I guess I will not set the changeable attribute to false and carefully
> ALWAYS set this two ("final") attributes after creating them using the
> generated factory.
Yes. You might add a factory method where the two feature's values are
specified as arguments as a convenience...
>
> Is it the "right" way to do ?
Yes.
>
> Note: I was reviewing some part of my code after reading the excellent
> "Effective Java" book and was trying to apply it. Here it concerns the
> item 15 "Minimize mutability" but it seems, as you said, this item is
> not compatible with EMF framewrok.
Yes, not so much.
>
> Regards,
>
> Manu

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