From: Shannon Fang <xrfang@...>
Date: 2002-12-01T05:49:19+09:00
Subject: Re: Ruby Document

Hi Bill,

I get to know symbol more and more by talking with you ruby gurus... :)
I know some of your examples, but still confusing :-(

On Sun, 1 Dec 2002 04:05:36 +0900
"Bill Kelly" <billk@cts.com> wrote:

> irb> "some_symbol".intern
> :some_symbol
This is what I don't understand. "some_symobol" is a instant value,
without a name. why the system assign a symbole :some_symbol to it?
So if I have a string "This is a test" then the intern will be
:This_is_a_test? That's sort of arbitrary...

Relating to your explaination, and previous messages, I still have some vital
question about understanding symbol:

1. I tested using IRB, it seems that a symbol is not related to the name.
For example,

irb(main):001:0> p :a.id
3602702
nil
irb(main):002:0> a=3
3
irb(main):003:0> p a.id
7
nil
irb(main):004:0> p :a.id
3602702
nil
irb(main):005:0>

It seems that I can create a symbol at any time, and it is not related
to the name. For example, after a=3, :a still point to the same place.
It seems that I have no way to use :a to reference to a? I am really
confused... :((

2. I guessed some usage of symbol in your explanation. Please have a
look at the following javascript code:

<html>
<body>
<script>
a=3
b=6
c=prompt("which var do you want?","a")
alert(c)
alert(eval(c))
</script>
</body>
</html>

In the first alert, it will give out the name of the var you choose, but
the second will give out the value of the var you choose. I vaguely
guessed the use of symbol is related to this purpose. Can you implement
the above JavaScript code in Ruby? Is it related to the use of symbol?

Thanks a lot! Any ruby guru pls give me some hints!

Shannon