Programming Question

agree at carltonfields.com agree at carltonfields.com
Fri Apr 9 14:35:22 UTC 1999


I'm not sure that's right either.  In kpgrant's example as understood, className species would always be an instance of class String, which instance containrf the <name> of the class he hoped to instantiate.  

As a concrete exampe, compare:

		'OrderedCollection' species new  

which generates an empty String object, with

		(Smalltalk at: 'OrderedCollection' asSymbol) new

which generates an empty OrderedCollection object.

-----Original Message-----
From:	MIME :rlpa80 at email.sps.mot.com Sent:	Friday, April 09, 1999 10:07 AM
To:	kpgrant at mindspring.com
Cc:	squeak at cs.uiuc.edu
Subject:	Re: Programming Question

Kevin,

This is an answ3er from a newbie, but I do think it is correct.
You want to used the method "species" as shown below. I used this
technique in a fix to class Path that I posted recently.

Best Regards,

John-Reed Maffeo Mesa, Arizona

kpgrant at mindspring.com wrote:
> > Here's one I'm having trouble figuring out...
> > I have an object of class String something like the following:
> >   className := 'OrderedCollection'
> > What I want to do is something like:
> >   newObject := (className asClass) new

 newObject := className species new
> > Of course there is no such message as "asClass".  The problem
> is that I can find no way to cause newObject to become a new
> object of class OrderedCollection.  Basically, I've got a string
> object whose contents are the name of some class, and I need to be
> able to send class-side messages like "new" to whichever class
> is named in the string, but I can't seem to find a mechanism for
> doing this.
> > Thanks,
> -Kevin


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