From: "nobu (Nobuyoshi Nakada) via ruby-core" <ruby-core@...>
Date: 2023-09-18T13:23:17+00:00
Subject: [ruby-core:114797] [Ruby master Bug#19888] Can't change binding of a Proc coerced from a Method

Issue #19888 has been updated by nobu (Nobuyoshi Nakada).



Status changed from Open to Feedback



Converting `Method` to `Proc` is **not** copying the inner code literally into a new block.

`Method` is bound to the receiver, while `UnboundMethod` returned by `Module#instance_method` is not, as the names.



----------------------------------------

Bug #19888: Can't change binding of a Proc coerced from a Method

https://bugs.ruby-lang.org/issues/19888#change-104641



* Author: waiting_for_dev (Marc Busqu�)

* Status: Feedback

* Priority: Normal

* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

----------------------------------------

`instance_exec` or `instance_eval` can execute a given `Proc` in the context of the receiver. However, that's not true when the `Proc` has been coerced from a `Method`. In that situation, the binding is always tied to the original instance.



```ruby

class A

  def foo

    "from A"

  end

end



class B

  def foo

    "from B"

  end

end



A.new.instance_exec(&-> { foo }) # => from A

A.new.instance_exec(&B.new.method(:foo)) # => from B

A.new.instance_exec(&B.new.method(:foo).to_proc) # => from B

```



At first sight, that looks like a bug, as the transformation from `Method` to `Proc` is not complete.











-- 

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