From: Rick DeNatale <rick.denatale@...>
Date: 2008-03-22T22:11:46+09:00
Subject: Re: ruby19 and defined?

On 3/22/08, Sebastian Hungerecker <sepp2k@googlemail.com> wrote:
> Roger Pack wrote:
>  > I know there was an RCR related to this once.  Maybe it was accepted.
>
>
> You mean an RCR proposing that defined? return true, right?
>  The problem here is not that defined? returns true instead of "method" though.
>  The problem is that it returns true instead of nil for the method that doesn't
>  exist. I doubt that that behaviour was proposed in an RCR.

Hmmmm, not so sure that that's actually a bug.

I've not found a good definition for what define? is supposed to do
when given an expression instead of a simple term.  It certainly never
evaluated the expression.  I don't know that I've ever used it with an
expression, but my impression was that it works syntactically more
than semantically, so whether or not a given expression would raise an
exception when evaluated wouldn't affect whether the expression was
defined.  For example, I'd expect that

     defined?(1/0)

would not indicate that the expression was undefined just because it
represents a divide by zero.

Having just looked at the latest beta of Pickaxe 3, I notice that Dave
still has define? returning strings instead of true/nil, and the page
has the red header indicating that it's been updated for 1.9.

Personally, I'm unhappy if 1.9 is no longer returning a description of
the syntactical class of the argument to defined? seems like a loss of
valuable information, and I'd hope that it was the returning of nil
rather than 'method' which is a bug.


-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/