From: akr@...
Date: 2020-08-31T02:04:04+00:00
Subject: [ruby-core:99782] [Ruby master Feature#17122] Add category to	Warning#warn

Issue #17122 has been updated by akr (Akira Tanaka).


akr (Akira Tanaka) wrote in #note-13:

> But Ruby don't have "ignorable" argument that
> actual argument which corresponding formal argument may not be exist.

Maeda-sensei (@maeda) told me that Common Lisp has allow-other-keys which suppress keyword argument checking at function call.

http://www.lispworks.com/documentation/HyperSpec/Body/03_dada.htm
http://www.lispworks.com/documentation/HyperSpec/Body/03_daf.htm

```
% clisp
  i i i i i i i       ooooo    o        ooooooo   ooooo   ooooo
  I I I I I I I      8     8   8           8     8     o  8    8
  I  \ `+' /  I      8         8           8     8        8    8
   \  `-+-'  /       8         8           8      ooooo   8oooo
    `-__|__-'        8         8           8           8  8
        |            8     o   8           8     o     8  8
  ------+------       ooooo    8oooooo  ooo8ooo   ooooo   8

Welcome to GNU CLISP 2.49.92 (2018-02-18) <http://clisp.org/>

Copyright (c) Bruno Haible, Michael Stoll 1992-1993
Copyright (c) Bruno Haible, Marcus Daniels 1994-1997
Copyright (c) Bruno Haible, Pierpaolo Bernardi, Sam Steingold 1998
Copyright (c) Bruno Haible, Sam Steingold 1999-2000
Copyright (c) Sam Steingold, Bruno Haible 2001-2018

Type :h and hit Enter for context help.

[1]> (defun f (x &key y) (+ x y))
F
[2]> (f 1 :y 2)
3
[3]> (f 1 :y 2 :z 3 :allow-other-keys t)
3
[4]> (f 1 :y 2 :z 3)

*** - F: illegal keyword/value pair :Z, 3 in argument list.
      The allowed keywords are (:Y)
The following restarts are available:
ABORT          :R1      Abort main loop
Break 1 [5]> 
```

----------------------------------------
Feature #17122: Add category to Warning#warn
https://bugs.ruby-lang.org/issues/17122#change-87299

* Author: eileencodes (Eileen Uchitelle)
* Status: Open
* Priority: Normal
----------------------------------------
Deprecation warnings and other warnings in Ruby have a category (:deprecated, etc) but those categories aren't exposed or accessible. In the most recent Ruby 2.7 upgrade at GitHub we monkey patched `Warning#warn` to be able to turn warnings into exceptions. However, there was no way to tell which warnings were deprecations and which were other types of warnings.

I want to expose the `category` on the `Warning` module so that I'm able to monkey patch `Warning#warn` and treat deprecation warnings differently from other warnings without using a regex the strings.

Here's an example program demonstrating what I'd like to get from Ruby by implementing this feature:

```ruby
module Warning
  def self.warn(msg, category: nil)
    if category == :deprecated
      raise msg 
    else
      super
    end 
  end 
end

def ivar
  Object.new.instance_variable_get(:@ivar)
end

# Doesn't raise, but warns with verbose set
ivar

# Raises an error
Object.new.tainted?
```

The PR I worked on with @tenderlove is here: https://github.com/ruby/ruby/pull/3418

It moves the `Warning` module to be written in Ruby, updates `rb_warning_s_warn` to pass kwargs, and adds a `category` to `Warning#warn`. 



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