Bug #15646: method_defined? inside method_added behaves differently for `initialize`

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.0dev (2019-03-08 trunk 67194) [x86_64-darwin18]
• Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN

[alanwu (Alan Wu)]

Repro:

class MethodAddedSpecialCase
  def self.method_added(name)
    puts "#{name} added, method_defined?: #{method_defined?(name)}"
  end

  def hello
  end

  def initialize
  end
  
  def world
  end
end

Output:

hello added, method_defined?: true
initialize added, method_defined?: false
world added, method_defined?: true

[alanwu (Alan Wu)]

• Description updated (diff)

[alanwu (Alan Wu)]

Ah, I didn't know initialize is always private:

irb(main):001:0> class A
irb(main):002:1>   def initialize
irb(main):003:2>   end
irb(main):004:1> end
=> :initialize
irb(main):005:0> A.new.initialize
Traceback (most recent call last):
        4: from /opt/rubies/2.6.1/bin/irb:23:in `<main>'
        3: from /opt/rubies/2.6.1/bin/irb:23:in `load'
        2: from /opt/rubies/2.6.1/lib/ruby/gems/2.6.0/gems/irb-1.0.0/exe/irb:11:in `<top (required)>'
        1: from (irb):5
NoMethodError (private method `initialize' called for #<A:0x00007faedb0bf428>)

I think this fact should be documented at least.

[nobu (Nobuyoshi Nakada)]

I think it is documented somewhere, but can't remember where it is now.

Anyway, these methods are always defined as private, unless singleton methods.
initialize, initialize_copy, initialize_clone, initialize_dup, respond_to_missing?

[alanwu (Alan Wu)]

This behavior is from [Feature #6539]. Do you remember why these methods are made to be always private, instead of setting them to be private in Kernel only?
I don't think this rule make sense for BasicObject classes since they don't have #dup and #clone and #respond_to?:

class A < BasicObject
  public

  def initialize_dup
  end
end

A.new.initialize_dup # private method `initialize_dup' called

[nobu (Nobuyoshi Nakada)]

initialize isn't involved in [Feature #6539].
It has been always private since more earlier days, 1.1 at least.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed