From: Sam Duncan <sduncan@...>
Date: 2012-03-07T04:55:18+09:00
Subject: Re: Getting the class of an object.

On 07/03/12 08:48, Ralph Shnelvar wrote:
> Sam,
>
> Tuesday, March 6, 2012, 12:09:45 PM, you wrote:
>
> SD>  On 07/03/12 07:15, Robert Klemme wrote:
>>> You do not want the class but rather the kind of "foo".  "local
>>> variable" is not a class.  You can do
>>>
>>> irb(main):032:0>   class Bogey<   Dance
>>> irb(main):033:1>   def bar
>>> irb(main):034:2>   a=0
>>> irb(main):035:2>   printf "foo ->   %p\n", defined?(foo)
>>> irb(main):036:2>   printf "a ->   %p\n", defined?(a)
>>> irb(main):037:2>   printf "none ->   %p\n", defined?(none)
>>> irb(main):038:2>   end
>>> irb(main):039:1>   end
>>> =>   nil
>>> irb(main):040:0>   Bogey.new.bar
>>> foo ->   "method"
>>> a ->   "local-variable"
>>> none ->   nil
>>> =>   nil
> SD>  Great answer. I'm pretty new to Ruby and assumed that defined? returned
> SD>  a boolean. That'll learn me for not reading the manual.
>
> SD>  Sam
>
> Indeed, it is a great answer. Thanks Robert!
>
> Now where in online documentation can I find where "defined?" is documented?
>
> I see it explained on page 137 of the Pickaxe book but is there more formal documentation online?
>
> Also ... I find it interesting that I get a syntax error when I do
>    defined? defined?

Yeah, that is odd.

1.9.2p290 :001 > defined? defined?
SyntaxError: (irb):1: syntax error, unexpected $end
     from ~/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `<main>'
1.9.2p290 :002 > defined?(defined?)
SyntaxError: (irb):2: syntax error, unexpected ')'
     from ~/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `<main>'
1.9.2p290 :003 > defined? :defined?
  => "expression"

Sam