From: Robert Klemme <bob.news@...>
Date: 2005-06-13T00:40:31+09:00
Subject: Re: Only if the object exists

Gavin Kistner <gavin@refinery.com> wrote:
> On Jun 11, 2005, at 11:03 AM, Douglas Livingstone wrote:
>> On 6/11/05, Gavin Kistner <gavin@refinery.com> wrote:
>>> If I write code like this:
>>>    self.foo.bar if self.foo
>>> then ruby runs the #foo method twice. (Javascript is the same way.)
>>
>> I'd probably go for:
>>
>> result = foo
>> result.bar unless result.nil?
>>
>> If it has to go one one line, could be:
>>
>> t = foo and puts t.bar
>
> So you've added 1-2 more options to my list, but the intent of my
> post was not how to rewrite it differently, but to request  that
> perhaps the parser could be a little more extra-intelligent about
> determining the scope/guaranteed presence of the local variable.

Why change the parser if there are ways to do this that don't require such 
heavy language modifications?

Btw, here's another option if you need that pattern more often

class Dummy
  def method_missing(*a,&b) self end
end
DUMMY = Dummy.new

(foo || DUMMY).bar

Apart from that I'd go with the "and" variant:

tmp = foo and tmp.bar

Kind regards

    robert