From: Robert Klemme <bob.news@...>
Date: 2004-05-13T22:23:54+09:00
Subject: Re: C++ namespaces in Ruby


"Martin Elzen" <martinelzen@hotmail.com> schrieb im Newsbeitrag
news:Sea2-F4Ky3hrbn1KPvI00017abd@hotmail.com...
>
> Recently someone pointed out that in his opinion there was just one
thing
> Ruby was missing, which was something like C++ namespaces.  Someone else
> replied that in that case the OP should use Ruby modules.  That's not
> exactly true, IMO.  In C++ the most significant difference between
> namespaces and classes is that namespaces are open, and classes are
shut.

There are others: you can't instantiate a namespace.

> Meaning that you can always add things to an already defined namespace,
but
> you can not add anything to an existing class (unless you happen to have
the
> source code of that class).  In contrast, Ruby classes are always open,
you
> can always add things to them, etc. , so in that way Ruby classes are
like
> C++ namespaces.  IMO if you want to achieve C++-like namespaces in Ruby,
> you'd be best off by using a Ruby class.  A Ruby class also comes closer
to
> a C++ namespace than a Ruby module because a Ruby class can contain
> instances of objects, and as far as I know this isn't possible in a Ruby
> module.

>> module Foo
>>   SOMETHING = "something"
>>   @bar = "bar"
>>   def self.bar; @bar; end
>> end
=> nil
>> Foo::SOMETHING
=> "something"
>> Foo::bar
=> "bar"

I beg to differ: first, your statement isn't true (if I understood you
correctly).  Second, modules are not meant to be instantiated directly,
which is the same with C++ namespaces.

Kind regards

    robert