From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@...>
Date: 2023-07-13T15:06:11+00:00
Subject: [ruby-core:114166] [Ruby master Bug#19749] Confirm correct behaviour when attaching private method with `#define_method`

Issue #19749 has been updated by mame (Yusuke Endoh).


Discussed at the dev meeting. In conclusion, @matz said he would like to keep the status quo.

Method visibility is not an attribute of a method itself, but an attribute of the class to which the method belongs. Therefore, `X.define_method(:bar, method(:foo))` should not inherit the visibility of foo.

Currently, `Module#define_method` defines a private/protected method if the context is private/protected *and* if the class/module of the context is equal to the receiver of `define_method`. Otherwise, it defines a public method. This behavior is hard to document, though.

@matz discussed the behavior of `define_method` as follows:

1. Ideally, I want `define_method` to always define a public method. However, it is too late to change.
2. The next desirable behavior is to define a public method if the receiver of define_method is explicit (i.e., NODE_CALL), and to follow context visibility if it is not explicit (i.e., NODE_FCALL). However, Matz gave up this idea because @ko1 stated that it was difficult to implement efficiently.
3. The next next desirable is the current behavior.

----------------------------------------
Bug #19749: Confirm correct behaviour when attaching private method with `#define_method`
https://bugs.ruby-lang.org/issues/19749#change-103850

* Author: itarato (Peter Arato)
* Status: Open
* Priority: Normal
* ruby -v: 3.3.0
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
This issue is a special case of https://bugs.ruby-lang.org/issues/19745:

Should dynamically added private methods via `.singleton_class.send(:define_method,...` at the top-level be accessible publicly?

See the following example:

```ruby
def bar; end

foo = Object.new
foo.singleton_class.define_method(:bar, method(:bar))

foo.bar # No error.
```

The script above runs fine on latest Ruby 3.3. Is this correct to ignore the fact that the visibility in the caller context is the default top-level private visibility?

This came up during a TruffleRuby investigation (https://github.com/oracle/truffleruby/issues/3134) where the result for the same script is: `private method 'bar' called for #<Object:0xc8> (NoMethodError)`




-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/