From: Warren Brown <wkb@...>
Date: 2003-02-22T01:23:21+09:00
Subject: Re: Inconsistent behavior in Array methods

Bulat,

> WB> though Array#sort uses the object's <=> method.
> 
> are you sure? :)
> 
> class Fixnum
>   alias q <=>
>   def <=>x
>     -q(x)
>   end
> end
> 
> p [1,2,3,4].sort                  #=>[1, 2, 3, 4]
> p [1,2,3,4].sort {|a,b| a<=>b}    #=>[4, 3, 2, 1]

    Quite sure:

irb(main):001:0> RUBY_VERSION
=> "1.6.8"
irb(main):002:0> class A; end
=> nil
irb(main):003:0> [A.new,A.new].sort
NameError: undefined method `<=>' for #<A:0x8054cb4>
        from (irb):3:in `sort'
        from (irb):3


    There are special cases for Fixnum and String in Array#sort:

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);
}

retval = rb_funcall(a, cmp, 1, b);
return rb_cmpint(retval);

    - Warren Brown