From: "David A. Black" <dblack@...>
Date: 2009-02-07T21:49:21+09:00
Subject: Re: Module#=== vs Object#is_a?

On Sat, 7 Feb 2009, Peter Fitzgibbons wrote:

> HI All,
>
> Could somone explain the subtle difference between Module#=== and
> Object#is_a?
>
> I found a usage of === to test if an argument is Regexp or not... just want
> to know the restrictions.
> The code is beautiful...
>
> if Regexp === regexp_or_string

They're the same, in essence. === is bound to the C method rb_mod_eqq,
which looks like this:

static VALUE
rb_mod_eqq(VALUE mod, VALUE arg)
{
     return rb_obj_is_kind_of(arg, mod);
}

=== is usually a light wrapper around something, mainly so that the 
case construct can use it implicitly. (It always looks a bit odd to me
used explicitly, since it usually has semantics that don't relate to
anything that equal signs normally signify.)


David

-- 
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