[ruby-core:50356] [ruby-trunk - Bug #7475][Open] Unexpected behavior of Module#append_features on singleton class

[ruby-core:50356] [ruby-trunk - Bug #7475][Open] Unexpected behavior of Module#append_features on singleton class

[ernie (Ernie Miller)]

Issue #7475 has been reported by ernie (Ernie Miller).

----------------------------------------
Bug #7475: Unexpected behavior of Module#append_features on singleton class
https://bugs.ruby-lang.org/issues/7475

Author: ernie (Ernie Miller)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 1.9.3
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin12.2.0] 


A more involved explanation is available at http://erniemiller.org/2012/11/29/ruby-tidbit-include-vs-extend-with-module-class-variables/

In short, the handling of class variables (and constants) when a module is extended vs included is not as expected.

Example:

    module Foo
      @@foo = 'foo'
    end
 
    class Bar
      include Foo
    end

    class Baz
      extend Foo
    end

    Bar.class_variable_get :@@foo # => "foo"
    Baz.singleton_class.class_variable_get :@@foo # => NameError: uninitialized class variable @@foo in Class

We would expect constant and class variable lookup on the singleton class to work, but it doesn't. Both Rubinius and JRuby seem to behave as expected in this case.

Thanks!


-- 
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[ruby-core:50394] [ruby-trunk - Bug #7475] Unexpected behavior of Module#append_features on singleton class

[ernie (Ernie Miller)]

Issue #7475 has been updated by ernie (Ernie Miller).


Another quick set of observations from this morning:

    class Baz
      class << self
        Const = 'Const'
        @@foo = 'foo'
      end
    end

    Baz.class_variables.inspect # => [:@@foo]
    Baz.singleton_class.class_variables.inspect # => []
    Baz.singleton_class.class_variable_get :@@foo # => 'foo' ???
    Baz.const_get(:Const, false) rescue "Nope." # => 'Nope.'
    Baz.singleton_class.const_get(:Const, false) rescue "Nope." # => Const

    # Let's try setting it explicitly.
    Baz.singleton_class.class_variable_set :@@foo, 'foo'
    Baz.singleton_class.class_variables.inspect # => [] -- still "empty"

However, if we extend Foo on Baz, vs opening the singleton class with "class << self",  we can class_variable_set on the singleton and see it show up in the list of class variables, vs being empty.

All of this is to say that I think some unexpected weirdness is going on in rb_include_module and/or include_class_new.
----------------------------------------
Bug #7475: Unexpected behavior of Module#append_features on singleton class
https://bugs.ruby-lang.org/issues/7475#change-34221

Author: ernie (Ernie Miller)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 1.9.3
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin12.2.0] 


A more involved explanation is available at http://erniemiller.org/2012/11/29/ruby-tidbit-include-vs-extend-with-module-class-variables/

In short, the handling of class variables (and constants) when a module is extended vs included is not as expected.

Example:

    module Foo
      @@foo = 'foo'
    end
 
    class Bar
      include Foo
    end

    class Baz
      extend Foo
    end

    Bar.class_variable_get :@@foo # => "foo"
    Baz.singleton_class.class_variable_get :@@foo # => NameError: uninitialized class variable @@foo in Class

We would expect constant and class variable lookup on the singleton class to work, but it doesn't. Both Rubinius and JRuby seem to behave as expected in this case.

Thanks!


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

[ruby-core:52405] [ruby-trunk - Bug #7475] Unexpected behavior of Module#append_features on singleton class

[ko1 (Koichi Sasada)]

Issue #7475 has been updated by ko1 (Koichi Sasada).

Assignee set to matz (Yukihiro Matsumoto)
Target version changed from 1.9.3 to next minor

Matz, could you check it?

----------------------------------------
Bug #7475: Unexpected behavior of Module#append_features on singleton class
https://bugs.ruby-lang.org/issues/7475#change-36458

Author: ernie (Ernie Miller)
Status: Open
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: next minor
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin12.2.0] 


A more involved explanation is available at http://erniemiller.org/2012/11/29/ruby-tidbit-include-vs-extend-with-module-class-variables/

In short, the handling of class variables (and constants) when a module is extended vs included is not as expected.

Example:

    module Foo
      @@foo = 'foo'
    end
 
    class Bar
      include Foo
    end

    class Baz
      extend Foo
    end

    Bar.class_variable_get :@@foo # => "foo"
    Baz.singleton_class.class_variable_get :@@foo # => NameError: uninitialized class variable @@foo in Class

We would expect constant and class variable lookup on the singleton class to work, but it doesn't. Both Rubinius and JRuby seem to behave as expected in this case.

Thanks!


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

[ruby-core:52425] [ruby-trunk - Bug #7475] Unexpected behavior of Module#append_features on singleton class

[nobu (Nobuyoshi Nakada)]

Issue #7475 has been updated by nobu (Nobuyoshi Nakada).

Description updated


----------------------------------------
Bug #7475: Unexpected behavior of Module#append_features on singleton class
https://bugs.ruby-lang.org/issues/7475#change-36480

Author: ernie (Ernie Miller)
Status: Open
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: next minor
ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin12.2.0] 


=begin
A more involved explanation is available at ((<URL:http://erniemiller.org/2012/11/29/ruby-tidbit-include-vs-extend-with-module-class-variables/>))

In short, the handling of class variables (and constants) when a module is extended vs included is not as expected.

Example:

    module Foo
      @@foo = 'foo'
    end
 
    class Bar
      include Foo
    end

    class Baz
      extend Foo
    end

    Bar.class_variable_get :@@foo # => "foo"
    Baz.singleton_class.class_variable_get :@@foo # => NameError: uninitialized class variable @@foo in Class

We would expect constant and class variable lookup on the singleton class to work, but it doesn't. Both Rubinius and JRuby seem to behave as expected in this case.

Thanks!
=end



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

[ruby-core:94367] [Ruby master Bug#7475] Unexpected behavior of Module#append_features on singleton class

[merch-redmine]

Issue #7475 has been updated by jeremyevans0 (Jeremy Evans).

Status changed from Open to Closed

I believe this is not a bug, it is expected behavior.  Class variable lookup for singleton classes is different from regular classes.  Class variable lookup for singleton classes is (with example class A):

* Singleton Class (A.singleton_class)
* All Ancestors of Class (A.ancestors)

Note that this does not include modules included in the singleton class.

Class variable access is different for singleton classes because class variable access from the singleton class should access class variables in the class itself.

Class variable lookup could certainly be changed to include modules included in the singleton class, but that would be a separate feature request, and we would have to decide if we want to only include modules before the superclass's singleton class, or all modules and singleton classes before `Class`.  Please submit a feature request if you would like to change class variable lookup.

----------------------------------------
Bug #7475: Unexpected behavior of Module#append_features on singleton class
https://bugs.ruby-lang.org/issues/7475#change-80779

* Author: ernie (Ernie Miller)
* Status: Closed
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version: 
* ruby -v: ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin12.2.0] 
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
----------------------------------------
=begin
A more involved explanation is available at ((<URL:http://erniemiller.org/2012/11/29/ruby-tidbit-include-vs-extend-with-module-class-variables/>))

In short, the handling of class variables (and constants) when a module is extended vs included is not as expected.

Example:

    module Foo
      @@foo = 'foo'
    end
 
    class Bar
      include Foo
    end

    class Baz
      extend Foo
    end

    Bar.class_variable_get :@@foo # => "foo"
    Baz.singleton_class.class_variable_get :@@foo # => NameError: uninitialized class variable @@foo in Class

We would expect constant and class variable lookup on the singleton class to work, but it doesn't. Both Rubinius and JRuby seem to behave as expected in this case.

Thanks!
=end




-- 
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