From: Robert Klemme <bob.news@...>
Date: 2004-05-28T22:00:35+09:00
Subject: Re: Struct derivation


"Philipp Kern" <trash@philkern.de> schrieb im Newsbeitrag
news:slrncbbbls.adl.trash@o2.net.philkern.de...
> On 2004-05-27, Alan Chen <aero6dof@yahoo.com> wrote:
> > I could be wrong, but I think you actually want:
> > class X < Struct.new(:foo,:bar)
> >   def initialize; end
> > end
>
> You're right. However it should be written class X < Struct.new("X",
:foo, :bar)

I'd rather don't do that if you're just interested in inheriting from this
struct.  Because Struct.new("X", :foo, :bar) creates a named struct:

12:09:03 [ContentReporter_BRANCH]: irbs
>> x = Struct.new("X", :foo, :bar)
=> Struct::X
>> x
=> Struct::X
>> Struct.constants
=> ["X", "Tms"]

> or something like that. Like this you could get around the warnings Ruby
issues
> when you redefine the class:
> (irb):6: warning: already initialized constant X

Which code gives you that warning?  I guess you did too much testing in
IRB and thus redefined the constant.  It works perfectly for me:

12:07:42 [ContentReporter_BRANCH]: irbs
>> class X < Struct.new(:foo,:bar)
>>   def initialize; end
>> end
=> nil
>> X
=> X
>> X.ancestors
=> [X, #<Class:0x101865f0>, Struct, Enumerable, Object, Kernel]

> > Or are you trying to create a new class X which can build new classes
like
> > struct?
>
> No, thank you Alan. That's what I searched. I misunderstood Struct a bit
|:

This can happen too easily.  Maybe they should've created another method
instead of overloading #new.  That can be really confusing in this
situation.

Regards

    robert