From: David Alan Black <dblack@...>
Date: 2000-12-23T14:03:02+09:00
Subject: [ruby-talk:7991] Re: Naming of "defined?"

On Sat, 23 Dec 2000, craig duncan wrote:

> I made a mistake in thinking there was something wrong with the `not
> defined?' predicate in:
> 
> craig@duncan:/usr/home/craig/ruby$ cat t.rb
> #!/usr/bin/ruby

Use the -w flag -- that way if matz introduces new warnings,
you'll be able to see them :-)

> def i
>   p "defining i as method"
> end
> p defined? i
> 
> i = 0 if not defined? i
> p defined? i
> 
> craig@duncan:/usr/home/craig/ruby$ t.rb
> "method"
> "local-variable"

But note what happens if you put parens after that last i:

   ....
   p defined? i()

output:

   "method"
   "method"

Here's a few more little test lines, in irb:

   irb 1> def i
   irb 2> "method i"
   irb 3> end
      ==>nil
   irb 4> public :i
      ==>Object
   irb 5> i = 123
      ==>123
   irb 6> self.i
      ==>"method i"
   irb 7> i
      ==>123
   irb 8> defined? self.i
      ==>"method"
   irb 9> defined? i
      ==>"local-variable"


So the local variable i masks, but does not actually replace, the
method i (as I understand it).


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav