Add Rails.application.deprecators

[jonathanhefner]

This adds a Rails.application.deprecators method that returns a managed collection of deprecators.

Individual deprecators can be added and retrieved from the collection:

Rails.application.deprecators[:my_gem] = ActiveSupport::Deprecation.new("2.0", "MyGem")
Rails.application.deprecators[:other_gem] = ActiveSupport::Deprecation.new("3.0", "OtherGem")

And the collection's configuration methods affect all deprecators in the collection:

Rails.application.deprecators.debug = true

Rails.application.deprecators[:my_gem].debug
# => true
Rails.application.deprecators[:other_gem].debug
# => true

Additionally, all deprecators in the collection can be silenced for the duration of a given block:

Rails.application.deprecators.silence do
  Rails.application.deprecators[:my_gem].warn    # => silenced (no warning)
  Rails.application.deprecators[:other_gem].warn # => silenced (no warning)
end

[rafaelfranca]

Maybe, but I'd not do it now and only do it later if it makes sense for the framework's own usage.

[rafaelfranca]

I think it makes sense.

[p8]

Hi @jonathanhefner.
I'm working on this weeks newsletter and want to include this PR.
Could you explain the use-case for this?
Is it for deprecating gem versions used by Rails?
So for example if we stop supporting dalli version 2, we add:
Rails.application.deprecators[:dalli] = ActiveSupport::Deprecation.new("2.0", "dalli")

[jonathanhefner]

@p8 Close, but it would be Dalli registering Rails.application.deprecators[:dalli] and generating warnings using that deprecator instance.

Before this PR, if a library created its own deprecator instance, users of the library would have to seek out and configure that instance separately from the global ActiveSupport::Deprecation instance. For example, if a library had:

MyGem.deprecator = ActiveSupport::Deprecation.new("2.0", "my_gem")

and a user wanted to set behavior = :raise for all deprecators, they would have to write:

ActiveSupport::Deprecation.behavior = :raise
MyGem.deprecator.behavior = :raise

And so on for each library with its own deprecator instance.

With this PR, each library can have an initializer like:

module MyGem
  class Railtie < ::Rails::Railtie
    initializer :deprecator do |app|
      app.deprecators[:my_gem] = MyGem.deprecator
    end
  end
end

And then the user will only have to write:

Rails.application.deprecators.behavior = :raise

Alternatively, if the user wants to change the behavior for a single deprecator, they now have a standard location to do so:

Rails.application.deprecators[:my_gem].behavior = :raise

And all the above also applies to the debug, disallowed_behavior, and silenced settings, as well as silence blocks.

[p8]

Ok clear. Thanks @jonathanhefner !