Use singletons for Env and TaskEnv, multitons for Project.

As a result, the plugin method #wants_projects_matching has been
refactored to return Project instances now so that Plugins can define
the parents of a node (among other things).#wants_projects_matching has
been refactored to return Project instances now so that Plugins can
define the parents of a node (among other
things).#wants_projects_matching has been refactored to return Project
instances now so that Plugins can define the parents of a node (among
other things).

.rubocop.yml

@@ -2,3 +2,10 @@ require: rubocop-rspec
 
 LineLength:
   Max: 120
+
+# This is a stupid lint. Yes, module_function is more explanatory than extend self for most use cases. However, the
+# former does not work if you want the methods to be able to call private methods; the latter does. See
+# https://practicingruby.com/articles/ruby-and-the-singleton-pattern-dont-get-along for a detailed explanation of the
+# problem.
+ModuleFunction:
+  Enabled: False

Gemfile.lock

@@ -80,6 +80,7 @@ GEM
       rainbow (>= 1.99.1, < 3.0)
       ruby-progressbar (~> 1.4)
     rubocop-rspec (1.3.0)
+    ruby-prof (0.15.8)
     ruby-progressbar (1.7.5)
     simplecov (0.10.0)
       docile (~> 1.1.0)
@@ -106,4 +107,5 @@ DEPENDENCIES
   rspec (~> 3.2)
   rubocop (~> 0.31)
   rubocop-rspec (~> 1.3)
+  ruby-prof (~> 0.15)
   shanty!

examples/test-static-project/Shantyfile

@@ -0,0 +1,2 @@
+option 'foo', 'bar'
+tag 'lux'

lib/shanty.rb

@@ -1,6 +1,5 @@
 require 'i18n'
 require 'pathname'
-require 'pry'
 
 require 'shanty/cli'
 require 'shanty/env'
@@ -12,13 +11,16 @@
 module Shanty
   # Main shanty class
   class Shanty
+    include Env
+
     # This is the root directory where the Shanty gem is located. Do not confuse this with the root of the repository
     # in which Shanty is operating, which is available via the TaskEnv class.
     GEM_ROOT = File.expand_path(File.join(__dir__, '..'))
 
     def start!
       setup_i18n
-      Cli.new(env, TaskSet.task_sets).run
+      require!
+      Cli.new(TaskSet.task_sets).run
     end
 
     private
@@ -27,9 +29,5 @@ def setup_i18n
       I18n.enforce_available_locales = true
       I18n.load_path = Dir[File.join(GEM_ROOT, 'translations', '*.yml')]
     end
-
-    def env
-      Env.new.tap(&:require!)
-    end
   end
 end

lib/shanty/cli.rb

@@ -1,7 +1,6 @@
 require 'commander'
 require 'i18n'
 require 'shanty/info'
-require 'shanty/task_env'
 require 'shanty/task_set'
 
 module Shanty
@@ -10,17 +9,12 @@ module Shanty
   class Cli
     include Commander::Methods
 
-    attr_reader :env, :task_sets
+    attr_reader :task_sets
 
-    def initialize(env, task_sets)
-      @env = env
+    def initialize(task_sets)
       @task_sets = task_sets
     end
 
-    def task_env
-      @task_env ||= TaskEnv.new(@env)
-    end
-
     def tasks
       @tasks ||= task_sets.reduce({}) do |acc, task_set|
         # FIXME: Warn or fail when there are duplicate task names?
@@ -70,7 +64,7 @@ def add_action_to_command(name, task, command)
     end
 
     def execute_task(name, task, options)
-      klass = task[:klass].new(task_env)
+      klass = task[:klass].new
       arity = klass.method(name).arity
       args = (arity >= 1 ? [options] : [])
       klass.send(name, *args)

lib/shanty/env.rb

@@ -4,9 +4,20 @@
 
 module Shanty
   #
-  class Env
+  module Env
+    # Idiom to allow singletons that can be mixed in: http://ozmm.org/posts/singin_singletons.html
+    extend self
+
     CONFIG_FILE = '.shanty.yml'
 
+    def clear!
+      @logger = nil
+      @environment = nil
+      @build_number = nil
+      @root = nil
+      @config = nil
+    end
+
     def require!
       Dir.chdir(root) do
         (config['require'] || {}).each do |path|

lib/shanty/plugin.rb

@@ -1,6 +1,11 @@
+require 'shanty/env'
+require 'shanty/project'
+
 module Shanty
   # Some basic functionality for every plugin.
   module Plugin
+    include Env
+
     def self.extended(plugin)
       plugins << plugin
     end
@@ -9,23 +14,19 @@ def self.plugins
       @plugins ||= []
     end
 
-    def self.discover_all_projects(env) # => Hash[Path, Array[Plugin]] where Path = String, Plugin = Class
-      projects = Hash.new { |h, k| h[k] = [] }
-      plugins.each_with_object(projects) do |plugin, acc|
-        paths = plugin.discover_projects(env) + plugin.wanted_projects(env)
-        paths.each { |path| acc[path] << plugin }
-      end
+    #
+
+    def self.discover_all_projects # => [Project]
+      plugins.flat_map(&:wanted_projects).uniq
     end
 
-    def self.with_graph(env, graph)
+    def self.with_graph(graph)
       plugins.each do |plugin|
-        plugin.with_graph_callbacks.each { |callback| callback.call(env, graph) }
+        plugin.with_graph_callbacks.each { |callback| callback.call(graph) }
       end
     end
 
-    def discover_projects(_env)
-      []
-    end
+    #
 
     def callbacks
       @callbacks ||= []
@@ -47,17 +48,21 @@ def with_graph_callbacks
       @with_graph_callbacks ||= []
     end
 
+    #
+
     def add_to_project(project)
       project.singleton_class.include(self)
       callbacks.each { |args| project.subscribe(*args) }
       tags.each { |tag| project.tag(tag) }
     end
 
+    #
+
     def subscribe(*args)
       callbacks << args
     end
 
-    def add_tags(*args)
+    def adds_tags(*args)
       tags.concat(args)
     end
 
@@ -70,27 +75,29 @@ def with_graph(&block)
       with_graph_callbacks << block
     end
 
-    def wanted_projects(env)
-      (wanted_projects_from_globs(env) + wanted_projects_from_callbacks(env)).uniq
+    #
+
+    def wanted_projects
+      (wanted_projects_from_globs + wanted_projects_from_callbacks).uniq.tap do |projects|
+        projects.each do |project|
+          project.plugin(self)
+        end
+      end
     end
 
     private
 
-    def wanted_projects_from_globs(env)
+    def wanted_projects_from_globs
       wanted_project_globs.flat_map do |globs|
         # Will make the glob absolute to the root if (and only if) it is relative.
-        Dir[File.expand_path(globs, env.root)].map do |path|
-          File.absolute_path(File.dirname(path))
+        Dir[File.expand_path(globs, root)].map do |path|
+          Project.new(File.absolute_path(File.dirname(path)))
         end
       end
     end
 
-    def wanted_projects_from_callbacks(env)
-      wanted_project_callbacks.flat_map do |callback|
-        callback.call(env).map do |path|
-          File.absolute_path(File.dirname(path))
-        end
-      end
+    def wanted_projects_from_callbacks
+      wanted_project_callbacks.flat_map(&:call)
     end
   end
 end

lib/shanty/plugins/bundler_plugin.rb

@@ -5,7 +5,7 @@ module Shanty
   module BundlerPlugin
     extend Plugin
 
-    add_tags :bundler
+    adds_tags :bundler
     wants_projects_matching '**/Gemfile'
     subscribe :build, :bundle_install
 

lib/shanty/plugins/rspec_plugin.rb

@@ -5,13 +5,14 @@ module Shanty
   module RspecPlugin
     extend Plugin
 
-    add_tags :rspec
+    adds_tags :rspec
     # By default, we'll detect RSpec in a project if has a dependency on it in a Gemfile or *.gemspec file. If you don't
     # use these files, you'll need to import the plugin manually using a Shantyfile as we can't tell if RSpec is being
     # used from the presence of a spec directory alone (this can be many other testing frameworks!)
     wants_projects_matching do
       Dir['**/{*.gemspec,Gemfile}'].each_with_object([]) do |dependency_file, acc|
-        acc << File.dirname(dependency_file) if File.read(dependency_file) =~ /['"]rspec['"]/
+        next unless File.read(dependency_file) =~ /['"]rspec['"]/
+        acc << Project.new(File.absolute_path(File.dirname(dependency_file)))
       end
     end
 

lib/shanty/plugins/rubocop_plugin.rb

@@ -5,7 +5,7 @@ module Shanty
   module RubocopPlugin
     extend Plugin
 
-    add_tags :rubocop
+    adds_tags :rubocop
     wants_projects_matching '**/.rubocop.yml'
     subscribe :test, :rubocop
 

lib/shanty/plugins/rubygem_plugin.rb

@@ -5,7 +5,7 @@ module Shanty
   module RubygemPlugin
     extend Plugin
 
-    add_tags :rubygem
+    adds_tags :rubygem
     wants_projects_matching '**/*.gemspec'
     subscribe :build, :build_gem
 

lib/shanty/plugins/shantyfile_plugin.rb

@@ -5,7 +5,7 @@ module Shanty
   module ShantyfilePlugin
     extend Plugin
 
-    add_tags :shantyfile
+    adds_tags :shantyfile
     wants_projects_matching '**/Shantyfile'
   end
 end

lib/shanty/project.rb

@@ -2,23 +2,42 @@
 require 'attr_combined_accessor'
 require 'call_me_ruby'
 
+require 'shanty/env'
+
 module Shanty
   # Public: Represents a project in the current repository.
   class Project
     include ActsAsGraphVertex
     include CallMeRuby
+    include Env
 
     attr_combined_accessor :name, :tags, :options
     attr_accessor :path, :parents_by_path
 
+    # Multiton or Flyweight pattern - only allow once instance per unique path.
+    #
+    # See https://en.wikipedia.org/wiki/Multiton_pattern, http://en.wikipedia.org/wiki/Flyweight_pattern, or
+    # http://blog.rubybestpractices.com/posts/gregory/059-issue-25-creational-design-patterns.html for more information.
+    #
+    # Note that this is _not_ currently threadsafe.
+    class << self
+      alias_method :__new__, :new
+
+      def new(path)
+        (@instances ||= {})[path] ||= __new__(path)
+      end
+
+      def clear!
+        @instances = {}
+      end
+    end
+
     # Public: Initialise the Project instance.
     #
-    # env  - The environment, an instance of Env.
     # path - The path to the project.
-    def initialize(env, path)
+    def initialize(path)
       fail('Path to project must be a directory.') unless File.directory?(path)
 
-      @env = env
       @path = path
 
       @name = File.basename(path)
@@ -39,7 +58,7 @@ def plugin(plugin)
 
     def parent(parent)
       # Will make the parent path absolute to the root if (and only if) it is relative.
-      @parents_by_path << File.expand_path(parent, @env.root)
+      @parents_by_path << File.expand_path(parent, root)
     end
 
     def tag(tag)

lib/shanty/task_env.rb

@@ -1,28 +1,22 @@
-require 'delegate'
-
 require 'shanty/plugin'
-require 'shanty/project'
 require 'shanty/project_linker'
 
 module Shanty
   #
-  class TaskEnv < SimpleDelegator
-    alias_method :env, :__getobj__
+  module TaskEnv
+    # Idiom to allow singletons that can be mixed in: http://ozmm.org/posts/singin_singletons.html
+    extend self
 
-    def graph
-      @graph ||= ProjectLinker.new(projects).link.tap do |graph|
-        Plugin.with_graph(env, graph)
-      end
+    def clear!
+      @graph = nil
     end
 
-    private
+    def graph
+      return @graph unless @graph.nil?
 
-    def projects
-      Plugin.discover_all_projects(env).map do |path, plugins|
-        Project.new(env, path).tap do |project|
-          plugins.each { |plugin| project.plugin(plugin) }
-          project.execute_shantyfile!
-        end
+      projects = Plugin.discover_all_projects.each(&:execute_shantyfile!)
+      @graph ||= ProjectLinker.new(projects).link.tap do |graph|
+        Plugin.with_graph(graph)
       end
     end
   end

lib/shanty/task_set.rb

@@ -1,11 +1,11 @@
+require 'shanty/env'
+require 'shanty/task_env'
+
 module Shanty
   # Public: Discover shanty tasks
   class TaskSet
-    attr_reader :task_env
-
-    def initialize(task_env)
-      @task_env = task_env
-    end
+    include Env
+    include TaskEnv
 
     # This method is auto-triggered by Ruby whenever a class inherits from
     # Shanty::TaskSet. This means we can build up a list of all the tasks