From: shugo@...
Date: 2015-12-17T01:32:21+00:00
Subject: [ruby-core:72198] [Ruby trunk - Bug #11828] [Feedback]	Object#freeze grid-locks Ruby

Issue #11828 has been updated by Shugo Maeda.

Status changed from Open to Feedback

Daniel P. Clark wrote:
> It seems safe to freeze most any class type in Ruby.  But if you call `Object.freeze` nothing from then on can be created in either class of method form.
> 
> Is this okay behavior to have in Ruby?
> 
> ~~~ruby
> Object.freeze
> 
> class A
> end
> # => RuntimeError: can't modify frozen #<Class:Object>
> ~~~

The above code tries to define the constant `A` in `Object`, so a RuntimeError is raised.

> ~~~ruby
> def x
> end
> # => RuntimeError: can't modify frozen class
> ~~~

The above code tries to define the method `x` in `Object`, so a RuntimeError is raised.

The following code avoiding such operations on `Object` works correctly even if `Object` is frozen:

```ruby
a = Class.new {
  def foo
    puts "foo"
  end
}

a.new.foo
```

> But all singleton instances are frozen.

What does "all singleton instances" mean?


----------------------------------------
Bug #11828: Object#freeze grid-locks Ruby
https://bugs.ruby-lang.org/issues/11828#change-55610

* Author: Daniel P. Clark
* Status: Feedback
* Priority: Normal
* Assignee: 
* ruby -v: 
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
It seems safe to freeze most any class type in Ruby.  But if you call `Object.freeze` nothing from then on can be created in either class of method form.

Is this okay behavior to have in Ruby?

~~~ruby
Object.freeze

class A
end
# => RuntimeError: can't modify frozen #<Class:Object>

def x
end
# => RuntimeError: can't modify frozen class
~~~

I noticed that Procs can still be defined.

~~~ruby
prc = proc {|a| a+1}

prc.call(4)
# => 5 
~~~


But all singleton instances are frozen.



-- 
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