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Bug #8297

extend & inherited class variable issue

Added by dunric (David Unric) about 7 years ago. Updated 10 months ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
ruby -v:
2.0.0p0
Backport:
[ruby-core:54463]

Description

=begin
By the current documentation, (({Object#extend})) method has to (only) add instance methods of a module given as a parameter.
In the following example, the class ((|C|)) is extended with module ((|M|)).
By (({class_variables})) method sent to singleton class of C also did inherit class variable ((|@@xyz|)).
However when inherited ((|@@xyz|)) is accessed, (({NameError})) exception is raised as it is was not initialized.

module M
@@xyz = 123
end
M.class_variables # [:@@xyz]
M.class_variable_get :@@xyz # 123 , so far so good

class C
extend M
end
p C.singleton_class.class_variables # [:@@xyz]
p C.singleton_class.class_variable_get :@@xyz # NameError exception

Either (({class_variables})) returns invalid array - ie. ((|@@xyz|)) was not inherited at all or (({class_variable_get})) ignores class variables inherited from module (when sent to a singleton).
=end
Prior Ruby versions like 1.9.3p392 does not suffer this issue as return with Module#class_variables returns an empty array.


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