1 files changed, 50 insertions, 42 deletions

diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index 492c519222..88dd932370 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -1,7 +1,9 @@
-require 'rails/initializable'
-require 'active_support/inflector'
-require 'active_support/core_ext/module/introspection'
-require 'active_support/core_ext/module/delegation'
+# frozen_string_literal: true
+
+require "rails/initializable"
+require "active_support/inflector"
+require "active_support/core_ext/module/introspection"
+require "active_support/core_ext/module/delegation"
 
 module Rails
   # <tt>Rails::Railtie</tt> is the core of the Rails framework and provides
@@ -103,6 +105,9 @@ module Rails
   #     end
   #   end
   #
+  # Since filenames on the load path are shared across gems, be sure that files you load
+  # through a railtie have unique names.
+  #
   # == Application and Engine
   #
   # An engine is nothing more than a railtie with some initializers already set. And since
@@ -111,7 +116,7 @@ module Rails
   #
   # Be sure to look at the documentation of those specific classes for more information.
   class Railtie
-    autoload :Configuration, 'rails/railtie/configuration'
+    autoload :Configuration, "rails/railtie/configuration"
 
     include Initializable
 
@@ -132,27 +137,19 @@ module Rails
       end
 
       def rake_tasks(&blk)
-        @rake_tasks ||= []
-        @rake_tasks << blk if blk
-        @rake_tasks
+        register_block_for(:rake_tasks, &blk)
       end
 
       def console(&blk)
-        @load_console ||= []
-        @load_console << blk if blk
-        @load_console
+        register_block_for(:load_console, &blk)
       end
 
       def runner(&blk)
-        @load_runner ||= []
-        @load_runner << blk if blk
-        @load_runner
+        register_block_for(:runner, &blk)
       end
 
       def generators(&blk)
-        @generators ||= []
-        @generators << blk if blk
-        @generators
+        register_block_for(:generators, &blk)
       end
 
       def abstract_railtie?
@@ -170,10 +167,6 @@ module Rails
         @instance ||= new
       end
 
-      def respond_to_missing?(*args)
-        instance.respond_to?(*args) || super
-      end
-
       # Allows you to configure the railtie. This is the same method seen in
       # Railtie::Configurable, but this module is no longer required for all
       # subclasses of Railtie so we provide the class method here.
@@ -181,11 +174,15 @@ module Rails
         instance.configure(&block)
       end
 
-      protected
-        def generate_railtie_name(string) #:nodoc:
+      private
+        def generate_railtie_name(string)
           ActiveSupport::Inflector.underscore(string).tr("/", "_")
         end
 
+        def respond_to_missing?(name, _)
+          instance.respond_to?(name) || super
+        end
+
         # If the class method does not have a method, then send the method call
         # to the Railtie instance.
         def method_missing(name, *args, &block)
@@ -195,6 +192,16 @@ module Rails
             super
           end
         end
+
+        # receives an instance variable identifier, set the variable value if is
+        # blank and append given block to value, which will be used later in
+        # `#each_registered_block(type, &block)`
+        def register_block_for(type, &blk)
+          var_name = "@#{type}"
+          blocks = instance_variable_defined?(var_name) ? instance_variable_get(var_name) : instance_variable_set(var_name, [])
+          blocks << blk if blk
+          blocks
+        end
     end
 
     delegate :railtie_name, to: :class
@@ -222,31 +229,32 @@ module Rails
 
     protected
 
-    def run_console_blocks(app) #:nodoc:
-      each_registered_block(:console) { |block| block.call(app) }
-    end
+      def run_console_blocks(app) #:nodoc:
+        each_registered_block(:console) { |block| block.call(app) }
+      end
 
-    def run_generators_blocks(app) #:nodoc:
-      each_registered_block(:generators) { |block| block.call(app) }
-    end
+      def run_generators_blocks(app) #:nodoc:
+        each_registered_block(:generators) { |block| block.call(app) }
+      end
 
-    def run_runner_blocks(app) #:nodoc:
-      each_registered_block(:runner) { |block| block.call(app) }
-    end
+      def run_runner_blocks(app) #:nodoc:
+        each_registered_block(:runner) { |block| block.call(app) }
+      end
 
-    def run_tasks_blocks(app) #:nodoc:
-      extend Rake::DSL
-      each_registered_block(:rake_tasks) { |block| instance_exec(app, &block) }
-    end
+      def run_tasks_blocks(app) #:nodoc:
+        extend Rake::DSL
+        each_registered_block(:rake_tasks) { |block| instance_exec(app, &block) }
+      end
 
     private
 
-    def each_registered_block(type, &block)
-      klass = self.class
-      while klass.respond_to?(type)
-        klass.public_send(type).each(&block)
-        klass = klass.superclass
+      # run `&block` in every registered block in `#register_block_for`
+      def each_registered_block(type, &block)
+        klass = self.class
+        while klass.respond_to?(type)
+          klass.public_send(type).each(&block)
+          klass = klass.superclass
+        end
       end
-    end
   end
 end