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Feature #6539

Updated by ko1 (Koichi Sasada) over 3 years ago

I feel there are inconsistencies in which methods are public and which are private. 

 For example: 

 ``` 
   

   obj = [] 
   prev = obj.instance_variable_get(:@foo) # allowed 
   obj.instance_variable_set(:@foo, nil)      # allowed 
   # But these are almost equivalent to: 
   prev = obj.remove_instance_variable(:@foo) 
     # => NoMethodError: private method `remove_instance_variable' called for []:Array 
 ``` 

 Another example: 

 ``` 
   

   module M 
     def foo 
       42 
     end 
   end 

   M.module_function :foo # private method `module_function' called for M:Module 
   M.extend M               # allowed 
   M.foo # => 42 
 ``` 

 Reverse example: 

 ``` 
   

   {}.method_missing :foo      # => private method `method_missing' called 
   {}.respond_to_missing? :foo, false     # => allowed, why? 
 ``` 

 Which methods should be private is a different question for Ruby than for apps and libraries; the "real" private methods of Ruby are in C! 
 For Ruby, I feel that a method should be private if it is *not meant to be called* except by Ruby itself (callbacks, etc...), or if it's a "global" methods of Kernel that is meant to be called directly (i.e. `puts` instead of `42.puts`) 

 Otherwise, it should be public. This includes methods like `Module#include`. 

 I don't know what the rationale was to make `include` and the like private. 

 I feel it is now quite common to use metaprogramming, e.g. to `include` modules from outside a class. It's part of a Class' API that it can be extended and modified, so these methods should be public. 

 Concrete proposal: 

 Should be made private: 

 ``` 
   Object and descendants 
     #initialize_clone 
     #initialize_dup 
     #respond_to_missing? 
   Rational & Complex 
     #marshal_dump 
     #marshal_load 
   Time 
     #_dump 
     ._load 
 ``` 

 Note that Delegate#initialize_{clone|dup} are already private 

 Should be made public: 

 ``` 
   

   Object 
     #remove_instance_variable 
   Module 
     #attr 
     #attr_reader 
     #attr_writer 
     #attr_accessor 
     #remove_const 
     #include 
     #remove_method 
     #undef_method 
     #alias_method 
     #public 
     #protected 
     #private 
     #module_function 
     #define_method 
 ``` 

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