Allow subscribing of listener(s) for the duration of a block [8]

README.md

@@ -199,6 +199,21 @@ In a Rails app you might want to add your global listeners in an initalizer.
 
 Global listeners are threadsafe.
 
+## Temporary Global Listeners
+
+You can also globally subscribe a listener for the duration of a block.
+
+```ruby
+Wisper::TemporaryListeners.with(MyListener.new) do
+  # do stuff
+end
+```
+
+Any events broadcast within the block by any publisher will be sent to the
+listeners.
+
+To subscribe multiple listeners pass an array to `with`.
+
 ## Subscribing to selected events
 
 By default a listener will get notified of all events it can respond to. You

lib/wisper.rb

@@ -5,6 +5,7 @@
 require 'wisper/registration/object'
 require 'wisper/registration/block'
 require 'wisper/global_listeners'
+require 'wisper/temporary_listeners'
 
 module Wisper
   def self.included(base)

lib/wisper/publisher.rb

@@ -33,8 +33,12 @@ def global_registrations
       GlobalListeners.registrations
     end
 
+    def temporary_registrations
+      TemporaryListeners.registrations
+    end
+
     def registrations
-      local_registrations.merge(global_registrations)
+      local_registrations + global_registrations + temporary_registrations
     end
 
     def broadcast(event, *args)

lib/wisper/temporary_listeners.rb

@@ -0,0 +1,42 @@
+module Wisper
+  class TemporaryListeners
+    include Singleton
+
+    def with(listener_or_listeners, options = {}, &block)
+      add_listeners(Array(listener_or_listeners), options)
+      yield
+      clear
+    end
+
+    def registrations
+      Thread.current[key] ||= Set.new
+    end
+
+    def self.with(listener_or_listeners, options = {}, &block)
+      instance.with(listener_or_listeners, options, &block)
+    end
+
+    def self.registrations
+      instance.registrations
+    end
+
+    private
+
+    def clear
+      registrations.clear
+    end
+
+    def add_listeners(listeners, options)
+      listeners.each { |listener| add_listener(listener, options)}
+    end
+
+    def add_listener(listener, options)
+      registrations << ObjectRegistration.new(listener, options)
+    end
+
+
+    def key
+      '__wisper_temporary_listeners'
+    end
+  end
+end

spec/lib/temporary_global_listeners_spec.rb

@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+describe Wisper::GlobalListeners do
+  let(:listener_1) { double('listener') }
+  let(:listener_2) { double('listener') }
+  let(:publisher)  { Object.class_eval { include Wisper::Publisher } }
+
+  describe '.with' do
+    it 'globally subscribes listener for duration of given block' do
+
+      listener_1.should_receive(:success)
+      listener_1.should_not_receive(:failure)
+
+      Wisper::TemporaryListeners.with(listener_1) do
+        publisher.instance_eval { broadcast(:success) }
+      end
+
+      publisher.instance_eval { broadcast(:failure) }
+    end
+
+    it 'globally subscribes listeners for duration of given block' do
+
+      listener_1.should_receive(:success)
+      listener_1.should_not_receive(:failure)
+
+      listener_2.should_receive(:success)
+      listener_2.should_not_receive(:failure)
+
+      Wisper::TemporaryListeners.with([listener_1, listener_2]) do
+        publisher.instance_eval { broadcast(:success) }
+      end
+
+      publisher.instance_eval { broadcast(:failure) }
+    end
+  end
+end
+