From: Robert Klemme <bob.news@...>
Date: 2006-02-19T19:38:29+09:00
Subject: Re: Understanding ruby? need help

Chris Pine <chris@pine.fm> wrote:
> On 2/18/06, bbqbaker <none@noine.com> wrote:
>> is this kind of right?? thanks
>
> Yep, that's basically it.  Coming from C++, I also had a tough time
> with blocks at first (but they are so great, so it's worth the
> effort).

C++ might want to compare blocks with functors.  I like to think of them as 
anonymous functions with a closure.  Often the closure is't even needed, 
such in simple examples where the block only operates on its arguments.

> I wrote a tutorial that talks, among other things, about a somewhat
> different approach to understanding blocks and procs:
>
>   http://pine.fm/LearnToProgram/?Chapter=10

Chris, I can't see "yield" mentioned on that page.  Is it just me, did I 
overlook it?  Is this intentionally?  I mean, "yield" would be the first 
thing that I'd describe on such a page; IMHO it's the default way to go when 
passing blocks to methods (it's also the fastest AFAIK).  I only use &block 
if I have to store the block in a variable and / or have to pass it on to 
another (recursive) method call.

> and, of course, it's also covered in my book:
>
>   http://www.pragmaticprogrammer.com/titles/fr_ltp/
>
> (The book covers what's in the tutorial, but considerably more in
> depth, and with the benefit of the feedback I got from the tutorial
> (which came first), as well as covering things that never made it into
> the tutorial.)
>
> Essentially, what I found confusing was "yield".  Once you look at the
> problem from the angle of little functions (like the C++ function you
> wrote) that you pass around explicitly, it makes more sense (to me, at
> least).
>
> Once I wrapped my head around that, it wasn't hard to see yield and
> the "do |...| code-code-code end" syntax as just shortcuts to make the
> whole process easier to program.

If you look at the block as anonymous function it's clear that one needs a 
special syntax to invoke it (can't use the name).  That's exactly what 
"yield" does.

> And for the record, I still think "yield" is a weird name for it.  :)

OTOH this has the advantage of drawing people's attention to it which 
probably makes reading code easier. :-)

Kind regards

    robert