From: brian ford <brixen@...>
Date: 2009-08-24T13:03:53+09:00
Subject: [ruby-core:25068] Re: Proposal: Simpler block format

Hi,

On Sun, Aug 23, 2009 at 4:53 PM, David A. Black<dblack@rubypal.com> wrote:
> 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).

I am desperately hoping for a miracle, that ->() will be removed.

Could we add def {} and see by usage which prevails? Or take a
world-wide vote (perhaps weighted by number of lines of Ruby code
written by the voter)?

Alas, if ->() stays, we will at least have an easy pick for the
ugliest bit of Ruby syntax.

BTW, could someone share code that effectively uses something like:

 call_method -> { proc_1 },
             -> { proc_2 },
             -> { proc_3 }

Cheers,
Brian

>
>
> 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
>
>