Add local gem laoder helper using file watcher in rails and evn driven relaoding in the gem

Author: davidmilo

.gitignore

@@ -0,0 +1,2 @@
+.DS_Store
+.envrc

my_namespace-my_gem/lib/my_namespace/my_gem.rb

@@ -2,7 +2,7 @@ source "https://rubygems.org"
 
 ruby "3.3.0"
 
-gem "my_namespace-my_gem", path: "../my_namespace-my_gem"
+gem "my_root_namespace-my_namespace-my_gem", path: "../my_root_namespace-my_namespace-my_gem"
 
 # Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
 gem "rails", "~> 7.1.3"

my_namespace-my_gem/lib/my_namespace/my_gem/version.rb

@@ -1,8 +1,9 @@
 PATH
-  remote: ../my_namespace-my_gem
+  remote: ../my_root_namespace-my_namespace-my_gem
   specs:
-    my_namespace-my_gem (0.1.0)
+    my_root_namespace-my_namespace-my_gem (0.1.0)
       http
+      zeitwerk
 
 GEM
   remote: https://rubygems.org/
@@ -269,7 +270,7 @@ DEPENDENCIES
   bootsnap
   debug
   importmap-rails
-  my_namespace-my_gem!
+  my_root_namespace-my_namespace-my_gem!
   propshaft
   puma (>= 5.0)
   rails (~> 7.1.3)

my_rails_app/Gemfile

@@ -1,5 +1,5 @@
 class DashboardController < ApplicationController
   def show
-    render inline: MyNamespace::MyGem.do_something
+    render inline: MyRootNamespace::MyNamespace::MyGem.do_something
   end
 end

my_rails_app/Gemfile.lock

@@ -0,0 +1,30 @@
+class LocalGemReloading
+  def self.setup_reloading_for_local_zeitwerk_gem(gem_name, local_gems_folder)
+    gem_path = Pathname.new(File.join(local_gems_folder, gem_name, "lib"))
+    puts gem_path
+    parts = gem_name.split("-")
+    gem_root = parts.delete(parts.last)
+    gem_namespaces = parts.map(&:camelize)
+    
+    puts gem_namespaces, gem_root 
+    loader_tag = "#{[gem_namespaces.join("::"), gem_root.underscore].join('-')}"
+    puts loader_tag
+    gem_loader = Zeitwerk::Registry.loaders.find { |loader| loader.tag == loader_tag }
+
+    file_watcher = ActiveSupport::FileUpdateChecker.new(gem_path.glob('**/*')) do
+      gem_loader.reload
+    end
+   
+    # Plug it to Rails to be executed on each request
+    Rails.application.reloaders << Class.new do 
+      def initialize(file_watcher)
+        @file_watcher = file_watcher
+      end
+   
+      def updated?
+        @file_watcher.execute_if_updated
+      end
+    end.new(file_watcher)
+    true
+  end
+end

my_rails_app/app/controllers/dashboard_controller.rb

@@ -1,4 +1,38 @@
 require "active_support/core_ext/integer/time"
+require_relative "../../app/utils/local_gem_reloading"
+
+def setup_reloading_for_local_zeitwerk_gem(gem_path)
+  # gem_lib_path = gem_path.join("lib")
+  # gem_loader = Zeitwerk::Loader.new
+  # gem_loader.push_dir(gem_lib_path)
+  puts Zeitwerk::Registry.loaders.inspect
+  gem_loader = Zeitwerk::Registry.loaders.find{ |loader| loader.tag == "MyNamespace-my_gem" }
+
+  puts gem_loader.inspect
+
+  # gem_loader = Zeitwerk::Registry.loader_for(gem_lib_path)
+  # gem_loader.enable_reloading
+  # gem_loader.setup
+
+  file_watcher = ActiveSupport::FileUpdateChecker.new(gem_path.glob('**/*')) do
+    gem_loader.reload
+  end
+ 
+  # Plug it to Rails to be executed on each request
+  Rails.application.reloaders << Class.new do 
+    def initialize(file_watcher)
+      @file_watcher = file_watcher
+    end
+ 
+    def updated?
+      @file_watcher.execute_if_updated
+    end
+  end.new(file_watcher)
+end
+
+# MyNamespace-my_gem
+
+
 
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
@@ -71,4 +105,7 @@
 
   # Raise error when a before_action's only/except options reference missing actions
   config.action_controller.raise_on_missing_callback_actions = true
+
+  LocalGemReloading.setup_reloading_for_local_zeitwerk_gem("my_root_namespace-my_namespace-my_gem", Rails.root.join("../"))
+  # setup_reloading_for_local_zeitwerk_gem(Rails.root.join('../', "my_root_namspace-my_namespace-my_gem"))
 end