[ruby-core:114831] [Ruby master Bug#19893] OpenStruct#respond_to? when true fails with NameError

20 Sep 2023

      Issue #19893 has been updated by znz (Kazuhiro NISHIYAMA).

I think you should define `respond_to_missing?` too.

```ruby
require 'ostruct'

class Dep
  def a
    "Hello from Dep"
  end
end

class FakeDep < OpenStruct
  def respond_to?(*args)
    super || Dep.new.respond_to?(*args)
  end

  def respond_to_missing?(*args)
    super || Dep.new.respond_to?(*args)
  end
end

FakeDep.new(a: []) # no error
```

----------------------------------------
Bug #19893: OpenStruct#respond_to? when true fails with NameError
https://bugs.ruby-lang.org/issues/19893#change-104675

* Author: msxavi (Emerson Xavier)
* Status: Open
* Priority: Normal
* ruby -v: 3.1.4
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
Hello,

I have a case where I overrode respond_to? on a subclass of OpenStruct because I this class to work as fake object.

```
class Dep
  def a
    "Hello from Dep"
  end
end
class FakeDep < OpenStruct
  def respond_to?(*args)
    super || Dep.new.respond_to?(*args)
  end  
end

FakeDep.new(a: [])

NameError: undefined method `a' for class `FakeDep'

      owner = method!(name).owner
              ^^^^^^^
from /usr/local/lib/ruby/3.1.0/ostruct.rb:245:in `method'
```

Is this a valid issue?

Also posted in https://github.com/ruby/ostruct/issues/55

-- 
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