Re: method names in 1.9

On Mon, Nov 12, 2007 at 02:48:07AM +0900, Rick DeNatale wrote:
> On Nov 11, 2007 5:29 AM, Matthew Boeh <[e-mail]> wrote:
> >
> > On Sun, Nov 11, 2007 at 07:06:44PM +0900, Jordi wrote:
>=20
> > > IIRC, in Ruby everything is message sending to objects even in the
> > > disguise of Object#method, at least conceptually.
> > >
> >
> > Conceptually, yes. But as far as I can tell, Object#respond_to? is effe=
ctively
> > equivalent to:
> >
> >   def respond_to?(message)
> >     !!method(message) rescue false
> >   end
>=20
>=20
> Oh I hope not.
>=20
> class PresidentOfTheUnitedStates
>   def trigger_global_thermonuclear_war
>       # code to end civilization as we know it.
>   end
> end
>=20
> PresidentOfTheUnitedStates.new.respond_to?(:trigger_global_thermonuclear_=
war)
>=20
>=20
> > in that Object#method_missing doesn't have any effect on it. So there i=
s a
> > concrete distinction between messages that map directly to methods and
> > messages handled by method_missing.
>=20
> I may misunderstand you, but if respond_to? really were equivalent to
> code above, then providing a response via method_missing WOULD affect
> it.
>=20
> --=20
> Rick DeNatale
>=20
> My blog on Ruby
> http://talklikeaduck.denhaven2.com/
>=20

I think you are misunderstanding me. My ersatz respond_to? does not call th=
e=20
method:

  q =3D Object.new
  def q.some_msg
    puts "some_msg called"
  end
  q.some_msg
  # "some_msg called"
  q.respond_to?(:some_msg)
  # =3D=3D> true
  # (nothing printed)
  def q.respond_to?(message)
    !!method(message) rescue false
  end
  q.respond_to?(:some_msg)
  # =3D=3D> true
  # (nothing printed)

And as regards method_missing:

  def q.method_missing(*args)
    p args
  end
  q.doesnt_exist
  # "[:doesnt_exist]"
  q.respond_to?(:doesnt_exist)
  # =3D=3D> false
  # (nothing printed)

Of course, there's no way that Object#respond_to? could behave differently,=
=20
since method_missing can (and is expected to) have side effects. I've alway=
s=20
had an idle interest in a duck type-friendly alternative to method_missing=
=20
called resolve_method or something similar; instead of actually performing =
the=20
expected behavior, it'd return a method object or anything that responds to=
=20
#call. Not something I'd move mountains for, but the lack of something like=
=20
that sometimes interferes with duck typing with method_missing-heavy APIs l=
ike=20
ActiveRecord.

--
Matthew Boeh