From: Rick DeNatale <rick.denatale@...>
Date: 2008-05-27T23:49:42+09:00
Subject: Re: OOP in Ruby?

On Tue, May 27, 2008 at 10:02 AM, Huw Collingbourne <huw@darkneon.com> wrote:
> Robert Dober wrote:
>> I agree upto here, but...
>>>- that is, just writing a block in code does not make it an
>>> instance of a Block (or Proc) class.
>> I however believe it does, if you write a block in Ruby it is always
>> passed on to a method
>
> Therein lies the difference. If you write a block in Smalltalk it has an
> independent existence.

In theory, but not necessarily in practice. In reality most Smalltalk
implementations will not reify the "block" arguments to methods like
ifTrue:, ifFalse:, ifTrue:ifFalse, and ifFalse:ifTrue:  instead they
cheat and compile test and branch bytecodes, and throw an exception if
the 'receiver' isn't a boolean.

http://talklikeaduck.denhaven2.com/articles/2008/05/21/what-would-you-miss-if-you-had-to-stop-using-ruby-and-go-back-to-smalltalk

The real difference, I think, is that in Smalltalk you can have
multiple arguments in a message which are coded as block literals,
where as in Ruby block literals can only be used as the final argument
to a method, and that that argument doesn't need to be explicitly
named if is invoked by the method using yield, or if it's ignored by
the method.

There's quite a discussion going on right now on ruby-core about the
esthetics of the new '->' "fallen over lambda" operator in 1.9 and
whether it would be better to allow a call like:

a.m({|b|...}, {|| ...})

where the |..| distinguish a block from a hash.

I don't know the ultimate fate of the proposal, but it DOES make ruby
syntax look a bit more like Smalltalk.

It makes me wonder what Ruby would look like had Matz chosen square
brackets rather than braces to delimit block literals.
-- 
Rick DeNatale

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