Comparable

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 <=>(anOther)
    str.size <=> anOther.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]

Public Instance Methods

obj < other → true or false click to toggle source

Compares two objects based on the receiver’s <=> method, returning true if it returns -1.

 
               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;
}

obj <= other → true or false click to toggle source

Compares two objects based on the receiver’s <=> method, returning true if it returns -1 or 0.

 
               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;
}

obj == other → true or false click to toggle source

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_equal(VALUE x, VALUE y)
{
    VALUE a[2];

    if (x == y) return Qtrue;

    a[0] = x; a[1] = y;
    return rb_rescue(cmp_eq, (VALUE)a, cmp_failed, 0);
}

obj > other → true or false click to toggle source

Compares two objects based on the receiver’s <=> method, returning true if it returns 1.

 
               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;
}

obj >= other → true or false click to toggle source

Compares two objects based on the receiver’s <=> method, returning true if it returns 0 or 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;
}

between?(min, max) → true or false click to toggle source

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

 
               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;
}

Commenting is here to help enhance the documentation. For example, sample code, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

Home Classes Methods

In Files

Methods

Class/Module Index

Comparable

Public Instance Methods