From: Mark Sparshatt <msparshatt@...>
Date: 2004-04-03T08:30:09+09:00
Subject: Re: Variable names

David King Landrith wrote:

>
> On Apr 2, 2004, at 5:22 PM, Jim Weirich wrote:
>
>>
>> David King Landrith said:
>>
>>> Let me restate the question:
>>>
>>> Whenever a method is called on an object, one and only one symbol is
>>> used to represent the object.
>>
>>
>> That statement is incorrect.
>
>
> Fair enough.  Does this work?
>
> Whenever a method is called on an object, one and only one expression 
> or symbol has been resolved to
> used to represent the object.
>
> And so:
>
> Is there any way to determine which symbol was representing the 
> expression or symbol at the time that the method was invoked?
>
> You'll forgive me if I feel like I'm playing twenty questions here.  
> Perhaps I should be asking: There seems to be some "thing" that the 
> interpreter determines refers to an object, and there can only be one 
> of these per method that is invoked.  How would we describe this "thing"?
>
This thing is a reference to the receiving object.  you can use self#id 
to find out this reference but you can't go from that to the variable or 
expression that was origionaly used.

>> Simple answer: NO
>
>
> I can see that this is also the answer to the restated question I ask 
> above.
>
> Just out of curiosity: At what point does the interpreter discard the 
> expression that it been evaluated to represent the object?


Presumably as soon as it has been evaluated.

you want to define a method so that this works

class X
    def meth()
       p self.magic
    end
end

x = X.new
x.meth #=> x

the problem is this is the moral equivelent of

def meth(self)
   p self.magic
end

x = x.new
meth(x)  #=> x

within meth it just knows there is an object called self, it has no 
knowledge of the fact that elsewhere in the program this object is 
reffered to as x.


--
Mark Sparshatt