From: "toulax@..." <toulax@...>
Date: 2007-02-16T21:15:15+09:00
Subject: Re: Ruby Syntax - One::Two

On Feb 16, 8:26 am, Stefano Crocco <stefano.cro...@alice.it> wrote:
> Alle venerd� 16 febbraio 2007, tou...@gmail.com ha scritto:
>
>
>
> > I'm a newcomer to ruby and there's this little something I don't
> > really understand:
>
> > class One::Two
> > ...
> > end
>
> > Class One::Three
> > ...
> > end
>
> > On this example, what does "::" mean? If understand correctly it's
> > just sort of a naming convention to imply that both the Two and Three
> > classes belong to the same "group", as in Net::HTTP and Net::FTP.
> > So, in essence Two and Three are completely unrelated, and I'd not
> > even need to have a class named One for it to work, is that right?
>
> > If not, please tell me, what exactly is the purpose of "::" on class
> > names?
>
> > Thanks
>
> :: is the scope operator. It is used to access constants defined in a class or
> module. Since classes are constants, when you write class One::Two, you're
> defining the class Two inside One (where One can be a class or a module). If
> you didn't define One, the code class One::Two will give you a NameError,
> telling you that the constant One is not initialized:
>
> >> class One::Two
> >> end
>
> NameError: uninitialized constant One
>         from (irb):1
>
>
>
> Another example of the use of :: is
>
> puts Math::PI, which prints the value of the PI constant
>
> >> puts Math::PI
>
> 3.14159265358979
>
> Since PI belongs to the Math module, I couldn't have written puts PI. In fact,
> this raises an exception:
>
> >> puts PI
>
> NameError: uninitialized constant PI
>         from (irb):5
>
> I hope this helps.
>
> Stefano

I understand now, I didn't realize "class One::Two" actually defined
the constant Two inside One.
Thank you!