Issue #16345 has been updated by akr (Akira Tanaka).


jeremyevans0 (Jeremy Evans) wrote:

> > However there are several situations that
> > we can know a user is a developer (who write Ruby code):
> > 
> > * unit test
> > * irb
> 
> If irb is used, we can know that and change warning behavior.  However, many developers use pry, so changing warning behavior just in irb is not a solution as those developers will not see the warnings.
> 
> Likewise, if a test library from stdlib is used, we could know that and change warning behavior.  However, many developers use other test libraries, so changing warning behavior just in test libraries in stdlib is not a solution as those developers will not see the warnings.

Of course, we can enable deprecation warnings for
pry and other test libraries.




----------------------------------------
Feature #16345: Don't emit deprecation warnings by default.
https://bugs.ruby-lang.org/issues/16345#change-82836

* Author: akr (Akira Tanaka)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
We propose that Ruby doesn't emit deprecation warnings by default.

Deprecation warnings are only useful during development for updating Ruby version.
They are not useful during development with current Ruby.
It is especially frustrating when deprecated warnings are generated in gems.
Also, deprecation warnings are totally useless in production environment.

So, we want to emit deprecation warnings only in useful situations.

We propose a command line argument `-W:deprecated` (or `--warning=deprecated`)
and the following methods to enable/disable deprecation warnings.

```ruby
Warning.disable(:deprecated)
Warning.enable(:deprecated)
Warning.enabled?(:deprecated)
```

Currently we don't propose a method to generate a deprecation warning
because currently our main intent is to disable deprecation warnings for 
keyword arguments, and the warnings are generated in C level.

Background:

We talked about keyword arguments during a developer meeting (2019-11-12).
https://bugs.ruby-lang.org/issues/16333
We expect many deprecation warnings to be generated in Ruby 2.7.
They are not useful except for development for Ruby transition, and
they may block transition to Ruby 2.7.

So, we have consensus to disable deprecation warnings by default.
Our design is intentionally minimum because we need this feature for Ruby 2.7.

We chose `Warning.disable(:deprecated)` instead of
re-defining `Warning.warn` in order to avoid string object generation.

Of course, we expect to extend this feature:
Ruby-level deprecation warning generation,
warnings other than deprecation, 
file-based restriction of warning generation, etc.
But this issue doesn't contain them.




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