b.rb

[10] (pry) main: 0> show-source Array#sort_by

From: enum.c (C Method):
Number of lines: 31
Owner: Enumerable
Visibility: public

static VALUE
enum_sort_by(VALUE obj)
{
    VALUE ary;
    long i;

    RETURN_ENUMERATOR(obj, 0, 0);

    if (TYPE(obj) == T_ARRAY) {
    ary  = rb_ary_new2(RARRAY_LEN(obj));
    }
    else {
    ary = rb_ary_new();
    }
    RBASIC(ary)->klass = 0;
    rb_block_call(obj, id_each, 0, 0, sort_by_i, ary);
    if (RARRAY_LEN(ary) > 1) {
    ruby_qsort(RARRAY_PTR(ary), RARRAY_LEN(ary), sizeof(VALUE),
           sort_by_cmp, (void *)ary);
    }
    if (RBASIC(ary)->klass) {
    rb_raise(rb_eRuntimeError, "sort_by reentered");
    }
    for (i=0; i<RARRAY_LEN(ary); i++) {
    RARRAY_PTR(ary)[i] = RNODE(RARRAY_PTR(ary)[i])->u2.value;
    }
    RBASIC(ary)->klass = rb_cArray;
    OBJ_INFECT(ary, obj);

    return ary;
}
[12] (pry) main: 0> show-doc Array#sort

From: array.c (C Method):
Number of lines: 9
Owner: Array
Visibility: public
Signature: sort()

Returns a new array created by sorting self. Comparisons for
the sort will be done using the <=> operator or using
an optional code block. The block implements a comparison between
a and b, returning -1, 0, or +1. See also
Enumerable#sort_by.

   a = [ "d", "a", "e", "c", "b" ]
   a.sort                    #=> ["a", "b", "c", "d", "e"]
   a.sort {|x,y| y <=> x }   #=> ["e", "d", "c", "b", "a"]
[13] (pry) main: 0>