Ruby Language Singleton Class Reopening (monkey patching) Singleton Classes
Example
There are three ways to reopen a Singleton Class
- Using
class_evalon a singleton class. - Using
class <<block. - Using
defto define a method on the object's singleton class directly
class Example
end
Example.singleton_class.class_eval do
def foo
:foo
end
end
Example.foo #=> :foo
class Example
end
class << Example
def bar
:bar
end
end
Example.bar #=> :bar
class Example
end
def Example.baz
:baz
end
Example.baz #=> :baz
Every object has a singleton class which you can access
class Example
end
ex1 = Example.new
def ex1.foobar
:foobar
end
ex1.foobar #=> :foobar
ex2 = Example.new
ex2.foobar #=> NoMethodError
