From: Robert Klemme <bob.news@...>
Date: 2005-01-18T17:01:12+09:00
Subject: Re: Creating an instance from a variable


"Bertram Scharpf" <lists@bertram-scharpf.de> schrieb im Newsbeitrag 
news:20050117170506.GB13393@homer.bertram-scharpf...
> Hi Robert,
>
> Am Dienstag, 18. Jan 2005, 01:06:06 +0900 schrieb Robert Klemme:
>>
>> "Florian Gross" <flgr@ccan.de> schrieb im Newsbeitrag
>> news:351ujtF4fbbeiU1@individual.net...
>> > Peter Hickman wrote:
>> >
>> > > I have a class like this:
>> > >
>> > > class Builder
>> > >    def Builder.create( klass, data )
>> > >        return klass.new(data)
>> > >    end
>> > > end
>> > >
>> > > I want to call it as:
>> > >
>> > > x = Builder.create( "Fred", data )
>> >
>> > Why don't just do  x = Builder.create(Fred, data)?
>>
>> Why then not "Fred.new data"?
>> :-)
>
> I'm porting my Make replacement Bake to Ruby and I do something
> like
>
>    class Real ; ...
>    class Phony ; ...
>
>    b = Builder.create target, name, prereqs, cmd
>
> where `target' is either `Real' or `Phony'.

???  Why can't you do

b = target.new name, prereqs, cmd

I mean, a class *is* a factory for its instances.  If you don't have the 
requirement that the actual class of created instances might be different or 
want to keep that flexibility I don't see any added value in introducing a 
method for this.

Regards

    robert