[HooksManager] Introduction

lib/cocoapods.rb

@@ -40,6 +40,7 @@ module Pod
   autoload :Executable,                'cocoapods/executable'
   autoload :ExternalSources,           'cocoapods/external_sources'
   autoload :Installer,                 'cocoapods/installer'
+  autoload :HooksManager,              'cocoapods/hooks_manager'
   autoload :PodTarget,                 'cocoapods/target/pod_target'
   autoload :Project,                   'cocoapods/project'
   autoload :Resolver,                  'cocoapods/resolver'

lib/cocoapods/hooks_manager.rb

+module Pod
+
+  # Provides support for the hook system of CocoaPods. The system is designed
+  # especially for plugins. Interested clients can register to notifications by
+  # name.
+  #
+  # The blocks, to prevent compatibility issues, will receive
+  # one and only one argument: a context object. This object should be simple
+  # storage of information (a typed hash). Notifications senders are
+  # responsible to indicate the class of the object associated with their
+  # notification name.
+  #
+  # Context object should not remove attribute accessors to not break
+  # compatibility with the plugins (this promise will be honoured strictly
+  # from CocoaPods 1.0).
+  #
+  module HooksManager
+    class << self
+
+      # @return [Hash{Symbol => Proc}] The list of the blocks that are
+      #         registered for each notification name.
+      #
+      attr_reader :registrations
+
+      # Registers a block for the hook with the given name.
+      #
+      # @param  [Symbol] name
+      #         The name of the notification.
+      #
+      # @param  [Proc] block
+      #         The block.
+      #
+      def register(name, &block)
+        raise ArgumentError, 'Missing name' unless name
+        raise ArgumentError, 'Missing block' unless block
+
+        @registrations ||= Hash.new
+        @registrations[name] ||= Array.new
+        @registrations[name] << block
+      end
+
+      # Runs all the registered blocks for the hook with the given name.
+      #
+      # @param  [Symbol] name
+      #         The name of the hook.
+      #
+      # @param  [Object] context
+      #         The context object which should be passed to the blocks.
+      #
+      def run(name, context)
+        raise ArgumentError, 'Missing name' unless name
+        raise ArgumentError, 'Missing options' unless context
+
+        if @registrations
+          blocks = @registrations[name]
+          if blocks
+            blocks.each do |block|
+              block.call(context)
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/unit/hooks_manager_spec.rb

+require File.expand_path('../../spec_helper', __FILE__)
+
+module Pod
+  describe HooksManager do
+    before do
+      @hooks_manager = Pod::HooksManager
+    end
+
+    describe 'register' do
+      it "allows to register a block for a notification with a given name" do
+        @hooks_manager.register(:post_install) {}
+        @hooks_manager.registrations[:post_install].count.should == 1
+        @hooks_manager.registrations[:post_install].first.class.should == Proc
+      end
+
+      it "raises if no name is given" do
+        should.raise ArgumentError do
+          @hooks_manager.register(nil) {}
+        end
+      end
+
+      it "raises if no block is given" do
+        should.raise ArgumentError do
+          @hooks_manager.register(:post_install)
+        end
+      end
+    end
+
+    describe 'run' do
+      it "invokes the hooks" do
+        @hooks_manager.register(:post_install) do |options|
+          true.should.be.true
+        end
+        @hooks_manager.run(:post_install, Object.new)
+      end
+
+      it "handles the case that no listeners have registered" do
+        should.not.raise do
+          @hooks_manager.run(:post_install, Object.new)
+        end
+      end
+
+      it "handles the case that no listeners have registered for a name" do
+        @hooks_manager.register(:post_install) do |options|
+          true.should.be.true
+        end
+        should.not.raise do
+          @hooks_manager.run(:pre_install, Object.new)
+        end
+      end
+
+      it "raises if no name is given" do
+        should.raise ArgumentError do
+          @hooks_manager.run(nil, Object.new) {}
+        end
+      end
+
+      it "raises if no context object is given" do
+        should.raise ArgumentError do
+          @hooks_manager.run(:post_install, nil)
+        end
+      end
+    end
+  end
+end
+