From: shugo@...
Date: 2015-12-09T06:24:26+00:00
Subject: [ruby-core:71985] [Ruby trunk - Bug #11779] Module#using does not make sense as a method

Issue #11779 has been updated by Shugo Maeda.


bug hit wrote:
> > Nobu didn't explain that Module#using should work in methods.
> > Module#using is designed not for such dynamic use.
> 
> Note that when #using is called in a module_eval block, its effect is confined to the body of the block.  So why should it matter if module_eval is called from a method or top level or from another module/class?  ~~Regardless of where it's called, #using inside it works the same.~~  The call site does not influence what #using does nor is influenced by it.

Because refinement activation should be as static as possible.
It might be better to prohibit Module#using in module_eval.


----------------------------------------
Bug #11779: Module#using does not make sense as a method
https://bugs.ruby-lang.org/issues/11779#change-55394

* Author: bug hit
* Status: Feedback
* Priority: Normal
* Assignee: 
* ruby -v: 2.2.3
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
1. it can't be called from another method
2. the receiver must be self
3. since refinements are lexically scoped the self receiver must match the currently open class

#3 is particularly curious

```ruby
module Refinement
  refine String do
    def refined?
      true
    end
  end
end

module Foo
  def self.refined?
    ''.refined? rescue false
  end
end


module Bar
  def self.refined?
    ''.refined? rescue false
  end
  Foo.module_eval do
    using Refinement

  end
end

p Foo.refined? #false
```

The module_eval `#using` call does not raise (it's not from a method and the receiver is self), but evidently because currently open class does not match self, it does not do anything. So it should at least raise.

So `#using`, though a method, does not function as a method, which is misleading.



-- 
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