From: "David A. Black" <dblack@...>
Date: 2009-08-24T08:53:44+09:00
Subject: [ruby-core:25063] Re: Proposal: Simpler block format

Hi --

On Mon, 24 Aug 2009, Yehuda Katz wrote:
>
> The compelling this for me is that it makes methods that take multiple
> blocks easier for programmer to read. For programmer, one big confusion in
> Ruby is difference between proc, block, lambda and method. Unifying syntax
> for block and proc shows that they are really just same thing, with proc
> passed as parameter and block passed as special parameter.

I have to admit that this strikes me as a solution in search of a
problem, in that I've never had any trouble reading methods that take
Proc objects as arguments. Also, I think that with the unification of
block and method parameter semantics, things are getting a lot less
confusing as to the differences among them.

I don't consider a block to be the same thing as a proc, nor do I
consider it a method argument. The block is part of the method-call
syntax; in itself, it isn't an object (just as the argument list is
not, in itself, an object).

> Then whenever programmer sees { something } they know it is "proc" with
> lexical scope, and whenever programmer sees ->{ something } they know it is
> "lambda" with function scope.

One danger of { something } being a proc is that it does away with the
error message for odd-numbered hashes -- an edge case, admittedly, but
still.

> I would even be in favor of def { } as lambda syntax, which would make clear
> to programmer that this block behaves just like normal method. Then we have
> just two things: def for method-scope (def something() end and def { }) and
> bare { } for block scope.

Dave Thomas brought up the def { } thing at RubyConf 2005, I believe,
and got a big round of applause :-) It's definitely way better than
->() (which I still sort of hope will disappear, though my hope is
fading).


David

-- 
David A. Black / Ruby Power and Light, LLC / http://www.rubypal.com
Q: What's the best way to get a really solid knowledge of Ruby?
A: Come to our Ruby training in Edison, New Jersey, September 14-17!
    Instructors: David A. Black and Erik Kastner
    More info and registration: http://rubyurl.com/vmzN