From: Charles Oliver Nutter <headius@...>
Date: 2011-01-31T06:53:47+09:00
Subject: Re: why is overloading invalid in ruby.

On Sat, Jan 29, 2011 at 12:37 AM, Eric Christopherson
<echristopherson@gmail.com> wrote:
> Specifically, MacRuby has an extension to the usual hash parameters
> that seems pretty complicated to me, but allows it to interact fairly
> painlessly with Objective-C*. It basically allows you to define a
> method with named parameters. It's bewildering because a method
> invocation like "person.setFirstName('Gloria', { :lastName=>'Alvarez'
> })" actually calls a *different* method from
> "person.setFirstName('Gloria', lastName: 'Alvarez')" (the former is
> the regular Ruby hash argument type; the latter uses the
> MacRuby-specific keyed arguments. If no keyed-argument version of a
> method exists, it will just translate it into a hash-argument form.)

Laurent can correct me if I'm wrong, but I don't think ObjC's syntax
qualifies as true named arguments. In MacRuby/ObjC, a method call like

foo(bar:1, baz:2)

Is just a way of saying something like

foo_with_bar_with_baz(1, 2)

The method name and the argument names actually resolve to different
method bodies internally. In addition, the order is absolutely
crucial. The following two calls are not the same and will not end up
in the same target method:

foo(bar: 1, baz: 2)
foo(baz: 2, bar: 1)

Named arguments would allow you to call the *same* method with
different groups of names in any order.

- Charlie