From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2000-10-20T18:25:36+09:00
Subject: [ruby-talk:5704] Re: variable variables

On Fri, 20 Oct 2000, Guy N. Hurst wrote:

> Hi,
> 
> I am wondering if ruby has an equivalent to PHP's
> variable variables.
> 
> For example, in PHP, if you set $x="myvar", then

In Perl, $x is now a symbolic reference, but these give you rope
to hang yourself!

> $$x will be equivalent to $myvar, so you could set

This is like de-referencing in Perl.

> $myvar indirectly by setting $$x:
> 
> <?php
> $x="myvar"
> $$x="hi"	#-> $myvar == "hi"
> ?>

If you do it through methods, you can use the fact that assignment
makes 2 objects point at the same thing:
irb(main):011:0> myvar = "hello"
"hello"
irb(main):012:0> x = myvar
"hello"
irb(main):013:0> x.sub!("hello","hi")
"hi"
irb(main):014:0> myvar
"hi"
irb(main):015:0> 

but assigning the new string to x would make x a new object.
	[...]
> ----
> A similar feature in PHP is extract(), which takes an
> associative array and puts the keys into the symbol table
> with the associaated values as the contents of each newly
> generated variable.
> 
	[...]
If the keys are not strings, this would be a problem, I think.
If they are strings, the way I thought to do it doesn't work. So I
don't know.
> 
> Thanks,
> 
> Guy N. Hurst
> 
	Hugh
	hgs@dmu.ac.uk