From: Chad Fowler <chad@...>
Date: 2003-07-18T03:00:13+09:00
Subject: Re: What's the point?

On Fri, 18 Jul 2003, Brian Candler wrote:

> On Fri, Jul 18, 2003 at 02:17:42AM +0900, Phil Tomson wrote:
> > As to your other question about "why?"  - Sometimes I used to do this in 
> > Perl to localize some functionality within a method (..errr, function or 
> > subroutine in Perl parlance).  Usually this was in a sort of refactoring 
> > stage where I'd look at my sub and find that I had some duplicated code in 
> > it that I could collect into another sub-sub.
> 
> Beware, thar be demons.
> 
> sub foo {
>   my $x = $_[0];
>   sub bar {
>     print "x is $x\n";
>   }
>   bar();
> }
> 

In Ruby, the equivalent code seems to fail, with local variables not being 
accessible in nested methods.  For example:

irb(main):018:0> def go
irb(main):019:1>   1.upto(10) do |num|
irb(main):020:2*     def my_meth
irb(main):021:3>       puts "Printing #{num}"
irb(main):022:3>     end
irb(main):023:2>   end
irb(main):024:1> end
nil
irb(main):025:0> go
1
irb(main):026:0> my_meth
NameError: undefined local variable or method `num' for 
#<Object:0x2b992c8>
        from (irb):21:in `my_meth'
        from (irb):26
        from ?:0

This seems unintuitive to me.  I would expect variables declared in a 
parent method to be accessible in child methods.  Can someone tell me why 
I'm wrong?  I'm sure I am. :)

Chad