Ruby 中的 module_function 和 extend self异同

# test.rb
module MyModule
 def public_meth
  p "a public method, if the module is included to a class , can be call as object.public_meth"
 end
 def module_method
  p "a module method,can be called as module_name.module_method. but can not be call as object.module_method"
 end
 private
 def private_method_to_module_function
  p "a private_method, but can be call as module_name.module_method, because it was assigned to module_function"
 end
 def private_method
  p "I am a private method"
 end
 module_function :module_method, :private_method_to_module_function
end

MyModule.module_method
MyModule.private_method_to_module_function
begin
 MyModule.public_meth
rescue
 p "public method can not be called by module_name.public_meth"
end
begin
 MyModule.private_method
rescue NoMethodError
 p "private method can not be called by module_name.module_method"
end

class MyClass
 include MyModule
end

obj = MyClass.new
obj.public_meth

begin
 obj.private_method
rescue NoMethodError
 p "private method in module can not be call by object.method_name"
end

begin
 obj.module_method
rescue NoMethodError
 p "module method can not be called by object.method_name, for object, module method is private instance method"
end

#调用
ruby test.rb
"a module method,can be called as module_name.module_method. but can not be call as object.module_method"
"a private_method, but can be call as module_name.module_method, because it was assigned to module_function"
"public method can not be called by module_name.public_meth"
"private method can not be called by module_name.module_method"
"a public method, if the module is included to a class , can be call as object.public_meth"
"private method in module can not be call by object.method_name"
"module method can not be called by object.method_name, for object, module method is private instance method"

#!/usr/bin/env ruby
# encoding: utf-8
# test_extend.rb
module MyModule
 extend self
 def public_meth
  p "a public_method extended by self can be called by module_name.public_meth and object.public_meth, included by a class"
  private_method
 end
 private
 def private_method
  p "a private method, can be call in module internal"
 end
end

class MyClass
 include MyModule
end

MyModule.public_meth

begin
 MyModule.private_method
rescue NoMethodError
 p "private method in extend self module can not be called module_name.private_method"
end

obj = MyClass.new
obj.public_meth

begin
 obj.private_method
rescue NoMethodError
 p "private method can not be called by object.private_method"
end

# 调用 ruby test_extend.rb
"a public_method extended by self can be called by module_name.public_meth and object.public_meth, included by a class"
"a private method, can be call in module internal"
"private method in extend self module can not be called module_name.private_method"
"a public_method extended by self can be called by module_name.public_meth and object.public_meth, included by a class"
"a private method, can be call in module internal"
"private method can not be called by object.private_method"