behavior=

Sets the behavior to the specified value. Can be a single value, array, or an object that responds to call.

Available behaviors:

raise

Raise ActiveSupport::DeprecationException.

stderr

Log all deprecation warnings to +$stderr+.

log

Log all deprecation warnings to Rails.logger.

notify

Use +ActiveSupport::Notifications+ to notify deprecation.rails.

silence

Do nothing.

Setting behaviors only affects deprecations that happen after boot time. Deprecation warnings raised by gems are not affected by this setting because they happen before Rails boots up.

ActiveSupport::Deprecation.behavior = :stderr
ActiveSupport::Deprecation.behavior = [:stderr, :log]
ActiveSupport::Deprecation.behavior = MyCustomHandler
ActiveSupport::Deprecation.behavior = ->(message, callstack) {
  # custom stuff
}