Re: [sc-dev] environments as prototypes (to know or not to know)

[Julian Rohrhuber <rohrhuber@xxxxxxxxxxxxxx>]

Hi Ron,

> I suppose you could make a separate PrototypeEnvironment that checks 
> for you (perhaps with a flag to turn it off
> in performance).
>
> I am still not sure if making extensive use of environments as 
> prototypes is such a good idea:


The main problem is that using Environments directly, either in class 
libraries or in runtime interpreted code, might be broken later due 
to a change in the class interface (by an extension or in Common). 
This breakage can lead to errors that are pretty difficult to trace. 
There needs to be a way to at least check this. Maybe the checking 
method I suggested does what you propose?




> 1.  It adds yet another layer of indirection that is not explicitly 
> integrated into the class hierarchy, making it
> tough to sort out what is going on.
>
> 2. There is the problem of collisions with the message name space of Object.
>
> 3. Keeping everything in Environments and doing the layering with 
> 'parent' (rather than using a class wrapper)
> is more transparent.  It also makes it possible to alter things for 
> a specific project without having to change the class
> library.
>
>
> Alberto's GUI class demonstrates the advantages of using environment 
> prototypes: it allows you to stick to standard
> coding style, so it is very easy to migrate existing work into a new 
> framework.
>
> GUIEvent and ConductorGUI demonstrates making the environment lookup explicit.
> If requires yet another paradigm (Event style coding) for the GUI.
> But it integrates the 'skin'
> with the GUI library and should be easier to extend.
>
> RJK
>
>
>
>
>
> On Aug 2, 2006, at 10:40 AM, Julian Rohrhuber wrote:
>
> > >  or, make a subclass of event that redefines put if you want to 
> > > keep maximum speed.
> >
> >  this means that ~tilde is not safe and also not
> >  (a: { myfunc }) style.
> >
> >
> >
> >  another way to do it is:
> >
> >  prototype {
> >  		var coll = this.methodCollisions;
> >  		^if(coll.isNil) {
> >  			this
> >  		} {
> >  			"This % cannot be used as prototype, because 
> > the following methods "
> >  			"are already defined in its class definition: 
> > %\n".postf(this.class, coll);
> >  		nil
> >  		}
> >  	}
> >
> >  methodCollisions { arg coll;
> >  		this.keysDo { |key| if(this.class.respondsTo(key)) { 
> > coll = coll.add(key) } };
> >  		proto !? { coll = proto. methodCollisions(coll) };
> >  		parent !? { coll = parent. methodCollisions(coll) };
> >  		^coll
> >  	}
> >
> >
> >  Then you just call
> >  .prototype when you want to be sure.
> >
> >  --
> >
> >
> >
> >
> >  .
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>
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