Method: Object#meta_class

Defined in:
lib/extlib/object.rb

#meta_class ⇒ Class

Extracts the singleton class, so that metaprogramming can be done on it.

Examples:

Setup
class MyString < String; end

MyString.instance_eval do
  define_method :foo do
    puts self
  end
end

MyString.meta_class.instance_eval do
  define_method :bar do
    puts self
  end
end

def String.add_meta_var(var)
  self.meta_class.instance_eval do
    define_method var do
      puts "HELLO"
    end
  end
end

MyString.new("Hello").foo #=> "Hello"

MyString.new("Hello").bar
  #=> NoMethodError: undefined method `bar' for "Hello":MyString

MyString.foo
  #=> NoMethodError: undefined method `foo' for MyString:Class

MyString.bar
  #=> MyString

String.bar
  #=> NoMethodError: undefined method `bar' for String:Class

MyString.add_meta_var(:x)
MyString.x #=> HELLO

Returns:

  • (Class) —

    The meta class.



62
 
# File 'lib/extlib/object.rb', line 62

def meta_class() class << self; self end end