From: Robert Dober <robert.dober@...>
Date: 2007-05-06T19:39:59+09:00
Subject: Re: How can I output an object/variable's name?

On 5/6/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 05.05.2007 23:19, John Joyce wrote:
> >
> > On May 6, 2007, at 6:06 AM, Robert Dober wrote:
> >
> >> On 5/5/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:
> >>> Suppose I have an object :
> >>>
> >>> a = 3
> >>>
> >>> I want to output the name a and the contents 3
> >>> Outputing the contents is no problem.
> >>> Is  there a method to output the name of the variable (object)
> >>
> >> No there is no way to output the name of a variable as a variable is
> >> one of the view concepts in Ruby that are not directly accessible from
> >> inside Ruby.
> >> When it comes to objects things change of course, some objects have
> >> name properties as e.g. classes
> >>
> >> irb(main):002:0> A=Class.new
> >> => A
> >> irb(main):003:0> A.name
> >> => "A"
> >> But be aware that it is the object and not the constant referring to
> >> it who has the name, as one can easily see...
> >> irb(main):007:0* b = Class.new
> >> => #<Class:0xb7d9ce54>
> >> irb(main):008:0> b.name
> >> => ""
> >> irb(main):009:0> C = b
> >> => C
> >> irb(main):010:0> C.name
> >> => "C"
> >> irb(main):011:0> b.name
> >> => "C"
> >>
> >> this is maybe a little bit confusing but that is what ruby does when a
> >> class object is assigned to a constant.
> >>
> >> Robert
> > Thanks Robert, but...
> >
> > That is totally confusing.
> > So what you are saying is that some objects have names and some do not.
> > Since everything (almost) is an object, which objects or which classes
> > would have names?
>
> No, he is saying that there are classes whose instances have a property
> called "name".  But this has absolutely nothing to do with variable
> names.
You are right Robert.
As a matter of fact I have produced yet another masterpiece of "Not
understanding OP's needs" :(
But I really loved Rick's way to explain things.
> If you think about it for a moment, it does not really make
> sense to want to get a variable name from an object.  Consider
>
> a = b = Object.new
>
> Now, there is just one instance - which "name" would you like to get?
>
<snip>

However John I still fail to see why you were happy with "eval" why
would you need it?
If you feel the need for eval in this context it is for 99% wrong,
maybe we can help you better if you describe a little bit more of your
needs.

Maybe all you need are objects with a name property and maybe it would
be best to use a different name (see how the two levels that
designation can be used might become *very* confusing) like e.g.
how_I_call_this_object (that is an extreme example of course).

Cheers
Robert

-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw