From: Brian Candler <B.Candler@...>
Date: 2004-10-06T18:38:29+09:00
Subject: Re: Fixnum <=> confusion

On Wed, Oct 06, 2004 at 04:43:05PM +0900, Robert Evans wrote:
> Now, if I call 1<=>2 then count increments. Does this mean that Fixnum 
> sorting does not call those operators? Thanks for any help.

Use The Source, Luke :-)

$ cd /v/build/ruby/ruby-1.8.1-2004.05.02/
$ less array.c

static int
sort_2(ap, bp)
...
    if (FIXNUM_P(a) && FIXNUM_P(b)) {
        if (a > b) return 1;
        if (a < b) return -1;
        return 0;
    }
    if (TYPE(a) == T_STRING && TYPE(b) == T_STRING) {
        return rb_str_cmp(a, b);
    }
...
static VALUE
sort_internal(ary)
    VALUE ary;
{
    qsort(RARRAY(ary)->ptr, RARRAY(ary)->len, sizeof(VALUE),
          rb_block_given_p()?sort_1:sort_2);
    return ary;
}

In other words: Array#sort, when called without a block, special-cases the
comparison of Fixnum to Fixnum and String to String, doing a hard-coded test
instead of calling the spaceship operator.

Try doing:
  array.sort { |a,b| a<=>b }
to force it to do the method call.

Regards,

Brian.