From: Robert Evans <robert.evans@...>
Date: 2004-10-06T19:29:27+09:00
Subject: Re: Fixnum <=> confusion

Aha. Thanks for the answer and the friendly reminder about the source.


On Oct 6, 2004, at 2:38 AM, Brian Candler wrote:

> 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.
>