Issue #11777 has been updated by Nobuyoshi Nakada.


Yes, this method is only for did_you_mean gem.

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Feature #11777: Change NameError#local_variables to return the list of local variables where the method is raised
https://bugs.ruby-lang.org/issues/11777#change-55359

* Author: Yuki Nishijima
* Status: Closed
* Priority: Normal
* Assignee: 
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Sasada-san and I talked about this briefly a few weeks ago, but I also wanted to let others know about this.

This change will make it possible to pull out the list of local variables where the exception is raised without TracePoint. The `did_you_mean` gem uses TracePoint, and the current code looks like this:

```ruby
# lib/did_you_mean.rb
TracePoint.new(:raise) do |tp|
  e = tp.raised_exception

  if SPELL_CHECKERS.include?(e.class.to_s) && !e.instance_variable_defined?(:@frame_binding)
    e.instance_variable_set(:@frame_binding, tp.binding)
  end
end.enable

# lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
def initialize(exception)
  ...
  @lvar_names = exception.frame_binding.local_variables

  ...
end
```

If we change `NameError#local_variables` as described it'll look like this:

```ruby
# lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
def initialize(exception)
  @lvar_names = exception.local_variables

  ...

end
```

The problem with TracePoint is that it's still a little buggy (also see #11668, #11667) and also makes Ruby slower [as reported by Sasada-san](https://twitter.com/_ko1/status/657599422566543360). I would like to change the behaviour of `NameError#local_variables` and remove the use of TracePoint from the gem entirely so we can make the gem much more stable.



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