Class: Brainguy::ManifestlyObservable

Inherits:
Module
  • Object
show all
Defined in:
lib/brainguy/manifestly_observable.rb

Overview

A custom Module subclass which acts like Observable, except with an event type manifest. This is a way to define an observable cladd with a known list of possible event types.

Examples:

class MyApiRequest
  include ManifestlyObservable.new(:success, :unauthorized, :error)
  # ...
end

Instance Method Summary collapse

Constructor Details

#initialize(*known_events) ⇒ ManifestlyObservable

Generate a new mixin module with a custom list of known event types.


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# File 'lib/brainguy/manifestly_observable.rb', line 18

def initialize(*known_events)
  # Look out, this gets a bit gnarly...
  @known_events = known_events
  # Define the module body
  super() do
    # First off, let's make sure we have basic Observable functionality
    include Observable

    # Now, we override #events to wrap it in some extra goodness
    define_method :events do

      # Let's see what the current subscription set object is
      subscription_set = super()

      # If there is already another ManifestlyObservable included further
      # up the chain...
      if subscription_set.is_a?(ManifestEmitter)
        # just add our event types to its subscription set
        subscription_set.known_types.concat(known_events)
        # But if this is the first ManifestlyObservable included...
      else
        # Wrap the subscription set in a ManifestEmitter
        @brainguy_events = ManifestEmitter.new(subscription_set)
        # Set up the known event types
        @brainguy_events.known_types.concat(known_events)
      end

      # No need to do all this every time. Once we've set everything up,
      # redefine the method on a per-instance level to be a simple getter.
      define_singleton_method :events do
        @brainguy_events
      end
      # Don't forget to return a value the first time around
      @brainguy_events
    end
  end
end

Instance Method Details

#to_s ⇒ String

Return a meaningful description of the generated module.

Returns:

  • (String) 

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# File 'lib/brainguy/manifestly_observable.rb', line 58

def to_s
  "ManifestlyObservable(#{@known_events.map(&:inspect).join(', ')})"
end