Configuration#subscribe, for Sourced::UI to auto-configure itself from Sourced configuration

Subscribers are triggered on Configuration#setup!

ex.

Sourced.config.subscribe do |config|
  # do something depending on Sourced configuration
end

Author: ismasan

lib/sourced/configuration.rb

@@ -62,12 +62,20 @@ def initialize
       @housekeeping_interval = 3
       @housekeeping_heartbeat_interval = 5
       @housekeeping_claim_ttl_seconds = 120
+      @subscribers = []
+    end
+
+    def subscribe(callable = nil, &block)
+      callable ||= block
+      @subscribers << callable
+      self
     end
 
     def setup!
       return if @setup
 
       @backend.setup!(self) if @backend.respond_to?(:setup!)
+      @subscribers.each { |s| s.call(self) }
       @setup = true
     end
 

spec/configuration_spec.rb

@@ -67,6 +67,18 @@
     expect(config.executor).to be_a(Sourced::AsyncExecutor)
   end
 
+  describe 'subscribers' do
+    it 'triggers subscribers on #setup!' do
+      executor_class = nil
+      config.subscribe do |c|
+        executor_class = c.executor.class
+      end
+      config.executor = :thread
+      config.setup!
+      expect(executor_class).to eq(Sourced::ThreadExecutor)
+    end
+  end
+
   describe '#executor=()' do
     specify ':async' do
       config.executor = :async