From: Aredridel <aredridel@...>
Date: 2005-02-02T03:42:31+09:00
Subject: Re: Binding precedence for first symbol arguments

On Tue, 2005-02-01 at 22:35 +0900, Martin DeMello wrote:
> Ryan Davis <ryand-ruby@zenspider.com> wrote:
> > 
> > On Jan 31, 2005, at 6:40 PM, Trans wrote:
> > 
> > > ...There are times when
> > > I just want one method that does a number of different but related
> > > things...
> > 
> > I gotta say wrt your original motivation, to me the need for this 
> > "feature" reeks of bad design. Even ignoring Eric's appeal for 
> > readability/separation of tokens, wanting a single method that "does a 
> > number of different but related things" says to me that maintainability 
> > and comprehensibility is going to be sacrificed in the medium-to-long 
> > run.
> 
> http://cgi.bramwell.plus.com/krblog/2004/07/avoid_boolean_p.html is a
> thought provoking read on adding-to-the-api versus adding-to-the-arglist


Hm. I think that in a language where you can't have any keyword-like
arguments, that makes total sense.

What T. is suggesting, I think, makes the API more verbose, but lets the
implementation treat it as booleans. . . which makes a lot of sense to
me. I've always hated code that had various factored out private helper
methods, or a large API of very similar functions. I can't see why

  def do_foo_with_arg(a)
    f = Foo.new
    f.arg = a
    f.run
  end

  def do_foo
    f = Foo.new
    f.run
  end

is any better than

  def do_foo(arg = nil)
    f = Foo.new
    f.arg = arg if arg
    f.run
  end

unless you needed to override the parts in a subclass. The second seems
far more succinct, though the example's nearly pathologically short.

For some reason, T.'s proposal makes a lot of sense to me -- I think of
whitespace as significant in that way already (the "foo.bar (baz)" vs
"foo.bar(baz)" distinction in the current parser makes total sense to
me) and I really like the way File.open:ro(filename) looks, and I would
enjoy an implementation that let me define it as

   def File.open(file, flags)

Or even, in a more overloaded method (line noise! Gasp!)

   def frob(arg, arg2, *args, **flags, &block)

Or, assuming it wasn't totally confusing to have some symbol overlap,
@flags.

Ari

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