[ruby-core:112195] [Ruby master Bug#19405] Prevent Use of include CustomModule in a Nested Class

Issue #19405 has been updated by jeremyevans0 (Jeremy Evans).



Status changed from Open to Rejected



This is not a bug, this is expected behavior. It is true in Ruby even if yo=
u don't define any classes:



```ruby

Object::Object::Object::Object::Object::Object::Object::Object::Object::Obj=
ect::Object::Object::Object::Object::Object::Object::Object::Object

# =3D> Object

```



If you want to prevent this, you could override `include`:



```ruby

module MyModule

  class MyClass

    A =3D 'A'

    B =3D 'B'



    def self.include(mod)

      raise if mod.const_get(name) =3D=3D self

      super

    end



    include MyModule

  end

end

```



You can even try to handle this globally:



```ruby

class Module

  def append_features(mod)

    raise if const_get(mod.name) =3D=3D mod

    super

  end

end

```



That only handles the direct inclusion case, it won't handle more complex c=
ases, or even other simple cases such as `module MyModule; MyModule =3D sel=
f end`.



In general, you should just accept that this is how Ruby is, and it isn't a=
 problem.



----------------------------------------

Bug #19405: Prevent Use of include CustomModule in a Nested Class=20

https://bugs.ruby-lang.org/issues/19405#change-101629



* Author: kyonides (Edwin Acu=F1a)

* Status: Rejected

* Priority: Normal

* ruby -v: ruby 2.7.5p203 (2021-11-24 revision f69aeb8314) [x86_64-linux-gn=
u]

* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

----------------------------------------

Bug present ever since **Ruby 1.8**.

Tested in **Ruby 2.7 and 3.0** as well.



I would like to request the developers to prevent any person from doing som=
ething as illogical and useless as the code I have provided you with right =
below.



``` ruby

module MyModule

  class MyClass

    A =3D 'A'

    B =3D 'B'

    include MyModule

  end

end

```



If you print something like:



``` ruby

puts MyModule::MyClass::MyClass::MyClass::MyClass::MyClass::MyClass::MyClas=
s::MyClass::MyClass::MyClass::MyClass::MyClass::MyClass::MyClass::MyClass::=
MyClass::B

```



Ruby will let you do it!



Why is it possible to chain the calls to MyClass class forever and ever?

It should throw an error for including the very same module and class where=
 the constants are nested.



Proposed Error Class:



"ModuleError: Class nested in module %s cannot call include method to add t=
he same module."



Or something the like. =3D_=3D=A1







--=20

https://bugs.ruby-lang.org/

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