[news.eclipse.tools.emf] Re: Default Value of an inherited EAttribute or

[Ed Merks <Ed.Merks@xxxxxxxxx>]

John,

Comments below.

John T.E. Timm wrote:
> So let's say that I define an EOperation "getFoo" in superclass A. And 
> then I define an EAttribute "foo" in subclass B. Are you suggesting 
> that I use the "Default Literal" option in conjunction with 
> OPTION_KEEP_DEFAULT_CONTENT on EAttribute foo in subclass B so that 
> the default gets serialized?
I'm just suggesting that when defining the feature just in "B" it's 
business as usual.  Define a default there and things will work as 
expected/always.
> In my particular application, I actually always want attr to be 
> serialized.
That options works well for that when you define a default too.
> So I guess what I am looking for is a way to "initialize" the value of 
> certain EAttributes and EReferences
Forget EReferences since that's incredibly unlikely to work well.
> immediately after instantiation without forcing the client code to do 
> it explicitly... In my particular model, I would have a superclass A 
> with subclasses B, C, and D where the only difference with B, C, and D 
> is that there are some constraints added and I want to "initialize" 
> the value of certain EAttributes and EReferences differently.
So the operation on A approach might work well then.
> Thanks,
>
> JT
>
> Ed Merks wrote:
>
> > John,
>
> > Comments below.
>
> > John T.E. Timm wrote:
> > > Ed:
> > >
> > > Ed Merks wrote:
> > >
> > > "Or have just an operation on A with a name that is overloaded by 
> > > the attribute in B..."
> > >
> > > Could you please expain how this would work?
> > On A you define an operation getFoo and in B you define a feature 
> > "foo" which will implement getFoo.
> > > What about attaching annotations to the class with all of the 
> > > default or fixed values and then customizing the generated EFactory 
> > > to do something like this:
> > >
> > > public ClassB createClassB() {
> > >    ClassB instance = new ClassBImpl();
> > >    // look at annotations to determine what needs to be initialized 
> > > here
> > >    instance.setAttr("someValue");
> > >    // ...
> > > }
> > You'll find that eIsSet returns true for "attr", so this value will 
> > be serialized, unlike what a true default would do.   If you unset 
> > "attr" and made a copy of ClassB, you'd find "attr" would be set in 
> > the copy but not in the original.
> > > Thanks,
> > >
> > > JT