Issue #13774 has been updated by bughit (bug hit).


nobu (Nobuyoshi Nakada) wrote:
> I think it is not a bug.
> 
> Local variables are not set up in the context of a binding from a method.
> 
> ```ruby
> $ ruby -e 'def m(v=12);v;end; p method(:m).to_proc.binding.eval("v")'
> Traceback (most recent call last):
> 	2: from -e:1:in `<main>'
> 	1: from -e:1:in `eval'
> -e:1:in `<empty iseq>': undefined local variable or method `v' for main:Object (NameError)
> ```

You are accessing a local variable in the method (which does not exist until the method is invoked), whereas I am accessing a variable outside the method, captured by the proc that defined the method, which does exist outside the invocation of the method. So your example does not explain the behavior that I am highlighting.

To try answer my own question, I can see how this might not be a bug if method.to_proc returns a proc that is no way related to the proc that defined the method. Such a proc simply forwards the args to the method and knows nothing about the original proc binding. I initially thought that it would somehow inherit the binding of the original proc. 

----------------------------------------
Bug #13774: for methods defined from procs, the binding of the resulting bound_method.to_proc does not have access to the original proc's closure environment
https://bugs.ruby-lang.org/issues/13774#change-69083

* Author: bughit (bug hit)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux]
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
```ruby
def foo
  o = Object.new
  local_var = 'local_var'
  method_lambda = ->{local_var}
  o.define_singleton_method(:lambda_method, &method_lambda)
  method_proc = o.method(:lambda_method).to_proc
  puts method_proc.()
  puts eval('local_var', method_lambda.binding)
  puts o.lambda_method
  puts eval('local_var', method_proc.binding) # undefined local variable or method `local_var'
end

foo
```

when executed as a method it has access to local_var as expected
but the binding of the bound method proc does not

in ruby 2.2.2 the above code crashes the vm



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