Ruby does not have an enumerated type, so a Slice enumeration is emulated using a Ruby class: the name of the Slice enumeration becomes the name of the Ruby class; for each enumerator, the class contains a constant with the same name as the enumerator. For example:
enum Fruit { Apple, Pear, Orange };
The generated Ruby class looks as follows:
class Fruit
include Comparable
Apple = # ...
Pear = # ...
Orange = # ...
def Fruit.from_int(val)
def to_i
def to_s
def <=>(other)
def hash
# ...
end
The compiler generates a class constant for each enumerator that holds a corresponding instance of Fruit. The from_int class method returns an instance given its integer value, while to_i returns the integer value of an enumerator and to_s returns its Slice identifier. The comparison operators are available as a result of including Comparable, which means a program can compare enumerators according to their integer values.
Given the above definitions, we can use enumerated values as follows:
f1 = Fruit::Apple
f2 = Fruit::Orange
if f1 == Fruit::Apple # Compare for equality
# ...
if f1 < f2 # Compare two enums
# ...
case f2
when Fruit::Orange
puts "found Orange"
else
puts "found #{f2.to_s}"
end
As you can see, the generated class enables natural use of enumerated values.