[ruby-core:109392] [Ruby master Feature#18930] Officially deprecate class variables

Issue #18930 has been updated by Dan0042 (Daniel DeLorme).


Eregon (Benoit Daloze) wrote in #note-8:
> ```ruby
> class A
>   @@foo = 1
>   
>   def self.foo
>     @@foo
>   end
> end
> 
> class B < A
>   @@foo = 2 # actually writes in A
> end
> 
> p A.foo # => 2, but should be 1
> ```

This is exactly the behavior that I want and expect from class variables. If I wanted one 'foo' per subclass I would use class instance variables.

It's not like I use class variables all *that* often, but I do use them more than global variables. So does that mean we should deprecate global variables? Class variables have their uses, and deprecating them is just removing a tool from the programmer's toolbox. Patronizing and disempowering.

----------------------------------------
Feature #18930: Officially deprecate class variables
https://bugs.ruby-lang.org/issues/18930#change-98541

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
Ruby's class variables are very confusing, and it seem many people agree they should be avoided (#18927).

How about we deprecate them officially?

Concretely:
* Mention in the documentation that class variables are deprecated and should be avoided/should not be used.
* Add a parse-time deprecation warning, now that we only see those with `Warning[:deprecation] = true` it seems reasonable to add.



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

Unsubscribe: <mailto:[e-mail]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>