The Comparable mixin is used by classes whose objects may be ordered. The class must define the <=> operator, which compares the receiver against another object, returning -1, 0, or +1 depending on whether the receiver is less than, equal to, or greater than the other object. If the other object is not comparable then the <=> operator should return nil. Comparable uses <=> to implement the conventional comparison operators (<, <=, ==, >=, and >) and the method between?.
class SizeMatters include Comparable attr :str def <=>(other) str.size <=> other.str.size end def initialize(str) @str = str end def inspect @str end end s1 = SizeMatters.new("Z") s2 = SizeMatters.new("YY") s3 = SizeMatters.new("XXX") s4 = SizeMatters.new("WWWW") s5 = SizeMatters.new("VVVVV") s1 < s2 #=> true s4.between?(s1, s3) #=> false s4.between?(s3, s5) #=> true [ s3, s2, s5, s4, s1 ].sort #=> [Z, YY, XXX, WWWW, VVVVV]
static VALUE
cmp_lt(VALUE x, VALUE y)
{
VALUE c = rb_funcall(x, cmp, 1, y);
if (rb_cmpint(c, x, y) < 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns -1.
static VALUE
cmp_le(VALUE x, VALUE y)
{
VALUE c = rb_funcall(x, cmp, 1, y);
if (rb_cmpint(c, x, y) <= 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns -1 or 0.
static VALUE
cmp_equal(VALUE x, VALUE y)
{
VALUE c;
if (x == y) return Qtrue;
c = rb_exec_recursive_paired_outer(cmp_eq_recursive, x, y, y);
if (NIL_P(c)) return Qfalse;
if (rb_cmpint(c, x, y) == 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns 0. Also returns true if obj and other are the same object.
static VALUE
cmp_gt(VALUE x, VALUE y)
{
VALUE c = rb_funcall(x, cmp, 1, y);
if (rb_cmpint(c, x, y) > 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns 1.
static VALUE
cmp_ge(VALUE x, VALUE y)
{
VALUE c = rb_funcall(x, cmp, 1, y);
if (rb_cmpint(c, x, y) >= 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns 0 or 1.
static VALUE
cmp_between(VALUE x, VALUE min, VALUE max)
{
if (RTEST(cmp_lt(x, min))) return Qfalse;
if (RTEST(cmp_gt(x, max))) return Qfalse;
return Qtrue;
}
Returns false if obj <=> min is less than zero or if anObject <=> max is greater than zero, true otherwise.
3.between?(1, 5) #=> true 6.between?(1, 5) #=> false 'cat'.between?('ant', 'dog') #=> true 'gnu'.between?('ant', 'dog') #=> false