From: Chris <chris@...>
Date: 2002-04-05T02:52:18+09:00
Subject: Re: Some ActiveRuby/RubyScript questions

In article <chris-CDEB43.11502404042002@corp.supernews.com>,
 Chris <chris@cmb-enterprises.com> wrote:

> In article <5.1.0.14.0.20020404153158.01dea910@pop3.bip.net>,
>  Liorean <Liorean@user.bip.net> wrote:
> 
> > Also, I'd like to know how to detect whether a property of an object exists 
> > or not, something of the kind:
> >    if(typeof document.all!='undefined'){/* some action or other... */}
> 
> an_array = []
> 
> if defined?(an_array.push)
>       #do something here
> end
> 
> or...
> 
> if x = defined? an_array.push
>    p x
> end
> 
> prints out "method"

There's also this nasty eval() solution:

class Object
   def has_attr?(attr_name)
      not defined?(eval("self.#{attr_name}")).nil?
   end
end

an_array = []
an_array.has_attr?("push")