Module: Comparable
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Included In:
| |
Defined in: | compar.c |
Overview
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]
Instance Method Summary
-
#<(other) ⇒ Boolean
Compares two objects based on the receiver's
<=>
method, returning true if it returns -1. -
#<=(other) ⇒ Boolean
Compares two objects based on the receiver's
<=>
method, returning true if it returns -1 or 0. -
#==(other) ⇒ Boolean
Compares two objects based on the receiver's
<=>
method, returning true if it returns 0. -
#>(other) ⇒ Boolean
Compares two objects based on the receiver's
<=>
method, returning true if it returns 1. -
#>=(other) ⇒ Boolean
Compares two objects based on the receiver's
<=>
method, returning true if it returns 0 or 1. -
#between?(min, max) ⇒ Boolean
Returns
false
if obj<=>
min is less than zero or if anObject<=>
max is greater than zero,true
otherwise.
Instance Method Details
#<(other) ⇒ Boolean
Compares two objects based on the receiver's <=>
method, returning true if it returns -1.
#<=(other) ⇒ Boolean
Compares two objects based on the receiver's <=>
method, returning true if it returns -1 or 0.
#==(other) ⇒ Boolean
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.
#>(other) ⇒ Boolean
Compares two objects based on the receiver's <=>
method, returning true if it returns 1.
#>=(other) ⇒ Boolean
Compares two objects based on the receiver's <=>
method, returning true if it returns 0 or 1.
#between?(min, max) ⇒ Boolean
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