Ruby | Comparable Module

In Ruby, the mixin of Comparable is used by the class whose objects may be ordered. The class must be defined using an operator which compare the receiver against another object. It will return -1, 0, and 1 depending upon the receiver. If the receiver is less than another object, then it returns -1, if the receiver is equal to another object, then it returns 0. If the receiver is greater than another object, then it returns 1. Comparable module use <=> to implement the conventional comparison operators(<, <=, ==, >=, and >) and the method between?

Example:

# Ruby program to illustrate
# comparable module

class Geeksforgeeks

# include comparable module
include Comparable
attr :name

    def <=>(other_name)
        name.length <=> other_name.name.length
    end

    def initialize(name)
        @name = name
    end
end

# creating objects
a1 = Geeksforgeeks.new("G")
a2 = Geeksforgeeks.new([3, 5])
a3 = Geeksforgeeks.new("geeks")

# using comparable operator
p a1 < a2

# using between? method
p a2.between?(a1, a3)
p a3.between?(a1, a2)

Output:

true
true
false

Instance Method

• < : It compares two objects based on the receiver’s method and return true if it return -1 otherwise return false.

  obj<other_obj

• <= : It compares two objects based on the receiver’s method and return true if it return -1 or 0 otherwise return false.

  obj<=other_obj

• == : It compares two objects based on the receiver’s method and return true if it return 0 otherwise return false.

  obj==other_obj

• > : It compares two objects based on the receiver’s method and return true if it return 1 otherwise return false.

  obj>other_obj

• >= : It compares two objects based on the receiver’s method and return true if it return 1 or 0 otherwise return false.

  obj>=other_obj

Example:

# Ruby program to illustrate
# use of comparisons

# defining class
class Geeksforgeeks

# include comparable module
include Comparable
attr :name

    def <=>(other_name)
        name.length <=> other_name.name.length
    end

    def initialize(name)
        @name = name
    end
end

# creating objects
a1 = Geeksforgeeks.new("G")
a2 = Geeksforgeeks.new("geeks")


# using < operator
p a1 < a2

# using <= operator
p a1 <= a2

# using == operator
p a1 == a2

# using >= operator
p a1 >= a2

# using > operator
p a1 > a2

Output:

true
true
false
false
false

• between? : This method returns false if the obj <=> min is less than or if obj <=> max is greater than zero. Otherwise, it returns true.

  obj.between?(min, max)

  Example:

  # Ruby program to illustrate
  # use of between?  method
  
  # using between? method
  p 7.between?(2, 6)
  p 'geeks'.between?('geeks', 'gfg')

  Output:

  false
  true
  

Reference: https://ruby-doc.org/core-2.2.0/Comparable.html