module Logging

  # The `Filter` class allows for filtering messages based on event
  # properties independently of the standard minimum-level restriction.
  #
  # All other Filters inherit from this class, and must override the
  # `allow` method to return the event if it should be allowed into the log.
  # Otherwise the `allow` method should return `nil`.
  class Filter

    # Returns the event if it should be allowed into the log. Returns `nil` if
    # the event should _not_ be allowed into the log. Subclasses should override
    # this method and provide their own filtering semantics.
    def allow( event )
      event
    end
  end
end