From: Hal Fulton <hal9000@...>
Date: 2003-09-14T16:13:04+09:00
Subject: Re: Dot versus double-colon

Gavin Sinclair wrote:
>>First, why is it this way?
> 
> File.open() is sending the message :open to object File.  The same
> cannot be said for the constant SEPARATOR.

Certainly it could be said. In fact, there is no way to tell
by looking at it whether it is in fact a method or a constant.

And a constant could be viewed as a method that always returns
the same value. Uniform access, you know.

> :: makes sense for namespaces - as in constant resolution.  It would
> not bother me one bit should :: be deprecated for method calls.

I'm accessing a value within an object. Sure, the value
happens to be constant. So what?

> 
>>By the way, for those who are wondering, this *is* possible:
> 
> 
>>   class File
>>     def self.SEPARATOR
>>       File::SEPARATOR
>>     end
>>   end
> 
> 
>>   File.SEPARATOR       # "/"
> 
> 
>>Even though it looks almost like recursion. Hmm, that raises
>>the question of why/how this works.
> 
> I'm sure you realise now.  It's because you've defined a method :)

You missed my point. Since the method File.SEPARATOR can be referred
to by the syntax File::SEPARATOR, then how does the method know that
it is not calling itself recursively?

>>And another issue is: One *could* write a little module that,
>>when included in a class, exposed all the class's constants in
>>this way. Within five minutes I had it "almost" working. I'll
>>bet someone in another timezone or with more caffeine could
>>have it working in three. Anyone?
> 
> 
> I'm happy for methods and constants to be accessed via different
> mechanisms (message passing vs namespace resolution) and for those
> mechanisms to be syntactically distinct.

I see what you mean. But I say: Why should a constant be anything
but a reader which happens always to return the same value?

Hal