From: Kenosis <kenosis@...>
Date: 2007-01-04T07:55:08+09:00
Subject: Re: Pickaxe question: "... on the way to true Ruby mastery."


jeffz_2002@yahoo.com wrote:
> Thanks David and Andre, I finally get it, and Andre, you're right about
> the nil/false idea in your response to my reponse.
>
> For anyone else following this thread, the idea is:
>
> - The first time the method is called, @foo doesn't exist.
>
> - @foo doesn't exist, so it's assigned a single-element array
> containing the value returned by the call to the private aliased
> original method.  This value can be anything, including an array,
> false, nil, whatever.
>
> - The 0th array element, which is just the return value of the function
> call, is returned.
>
> - The next time the method is called, @foo still exists, and is still a
> single-element array.  We again return the 0th element, which is the
> answer.
>
> The [0] is used because the result is stored in an array ... this gets
> around the original method returning nil or false, which would end up
> in a second call to the function, had we just naively used @foo ||=
> foo( *args, &block )..
>
> Thanks again.  It's pretty obvious, actually ... sigh.
>
> Funny, I still don't feel well on my way to mastery.  I actually feel
> dumber, in a way.
>
> jz

Welcome to the wonderful world of meta-programming in Ruby!  And don't
feel dumb.  As the saying goes: the more you know, the more you know
that you don't know.  Ask any true master of anything and that'll be
the answer they give you; if they're a >true< master.

Ken

PS. Check these out to continue your mastery...

http://www.erikveen.dds.nl/monitorfunctions/index.html
http://groups.google.com/group/comp.lang.ruby/browse_thread/thread/22b97167fe614efc/2627d192d2bf56d5?hl=en#2627d192d2bf56d5