From: dblack@...
Date: 2003-04-27T08:25:20+09:00
Subject: Re: block.call vs. yield

Hi --

On Sun, 27 Apr 2003, Hal E. Fulton wrote:

> ----- Original Message -----
> From: <dblack@superlink.net>
> To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
> Sent: Saturday, April 26, 2003 10:13 AM
> Subject: Re: block.call vs. yield
>
>
> > Maybe something like call_with_... or call_as... ?  (Not sure what the
> > ... would be.)
>
> call_as_block perhaps?? or just call_block ?

Another thought:

If Proc#call has method-like semantics, perhaps what's needed is a
method with block-like semantics -- namely, Block#call.  That, of
course, would also mean "Block" would be needed :-)

But in fact, there is a certain logic to this, I think:

  pr = Proc.new {|x,y| puts x,y}
  pr.call(1,2)                   # => 1\n2\n
  pr.call(1)                     # => error

but then:

  pr.to_block.call(1)            # => 1\nnil\n

Also, of course:

  b = Block.new {|x,y| puts x,y}
  b.call(1,2,3,4,5)              # => 1\n2\n


Quick and probably badly designed implementation:

  class Block < Proc
    private; def callback(*args); yield(args); end
    public;  def call(*args); callback(*args,&self); end
  end

  class Proc
    def to_block
      Block.new &self
    end
  end


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav