Feature #16699: Silence/ignore particular warnings from some parts of the code (in a .rb file)

• Status: Feedback
• Priority: Normal
• Assignee: -
• Target version: -

[shevegen (Robert A. Heiler)]

I would like to make it possible to briefly enable or disable particular warnings: those related to modifying a constant or a method.

It is possible to silence a specific warning as in:

SOME_CONSTANT = 42
old_verbose_value = $VERBOSE
$VERBOSE = nil
SOME_CONSTANT = 24
$VERBOSE = old_verbose_value

I needed to do so to redefine a method. I had to add an instance variable to that method. There are alternatives, e.g. including a module, or subclassing, but I wanted to just redefine the method as is, without incurring a warning message on the command line. The above way to re-assign $VERBOSE works fine. It should be kept. At the same time, though, looking at $variables is not that elegant, and it feels a tiny bit hackish too; plus, it may be useful if ruby users may use a more common idiom for this procedure.

I found out that rails has this:

https://apidock.com/rails/Kernel/silence_warnings

It may be elegant to have a method, be it in Kernel, or in Warnings, or another particular name (silence_warnings is not a bad name).

There may be more use cases, but I am only thinking about these two use cases.

I refer ONLY to situations where the ruby developer would be aware that a warning would be silenced. I run with -w all the time, but not every warning is equally useful to me.

It may be helpful if you could comment a use case for something like this. It may be also helpful if others comment whether the use case may be useful
or not.

We can only settle for a single short method. Otherwise, the current way would be better.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Feedback

Warning.warn added in ruby 2.4 offers the core infrastructure that allows this. The warning gem (https://rubygems.org/gems/warning) offers a nice API to support the filtering of such warnings, assuming they are correctly prefixed by the filename in which the warning occurs. rb_warn and rb_warning in the C-API both use that format, as does Kernel#warn with the :uplevel option. Do you see a need for an additional feature in this area, and if so, what do you think the API should look like?

[sawa (Tsuyoshi Sawada)]

• Subject changed from Consider providing ruby developers with a way to specifically silence/ignore particular warnings from some parts of the code (in a .rb file) to Silence/ignore particular warnings from some parts of the code (in a .rb file)
• Description updated (diff)

[Eregon (Benoit Daloze)]

It's also worth noting that changing $VERBOSE is not thread-safe (it's a truly global variable) and might suppress more or less warnings than intended.