diff --git a/.env.sample b/.env.sample
index 07cbeee..8b6b453 100644
--- a/.env.sample
+++ b/.env.sample
@@ -11,7 +11,7 @@
 #--------------
 STIMULUS_DEBUG=false
 LOG_ACTIVE_RECORD=false
-LOG_ACTION_VIEW=true
+LOG_ACTION_VIEW=false
 
 # INTEGER=2
 # STRING=
diff --git a/config/initializers/hot_constants.rb b/config/initializers/hot_constants.rb
index ac039ae..101f809 100644
--- a/config/initializers/hot_constants.rb
+++ b/config/initializers/hot_constants.rb
@@ -3,6 +3,5 @@ return unless defined?(Rails::Server)
 require Rails.root.join('lib', 'hot_constants', 'hot_constants')
 
 HotConstants.initialize
-
-logger.info('hot constants initialized!')
-# TODO: provide kind of a callback method which provides new value of hot constant change
+HotConstants.on_change(:log_active_record) { |bool| ActiveRecord::Base.logger.level = bool ? :debug : :fatal }
+HotConstants.on_change(:log_action_view) { |bool| ActionView::Base.logger.level = bool ? :debug : :fatal }
diff --git a/lib/hot_constants/hot_constants.rb b/lib/hot_constants/hot_constants.rb
index e7bbdff..84ee5ec 100644
--- a/lib/hot_constants/hot_constants.rb
+++ b/lib/hot_constants/hot_constants.rb
@@ -7,6 +7,7 @@ module HotConstants
 
   class << self
     def initialize
+      @on_change_listeners = {}
       env_sample = Dotenv.parse('.env.sample') # TODO: able to detect add/remove, then either call define_method or undef_method!
       env_sample.each do |key, value|
         dkey = key.downcase
@@ -18,10 +19,16 @@ module HotConstants
     end
 
     def reload!
-      HOTENV.replace Dotenv.parse # detect true changes before processing block below (or yield)
+      HOTENV.replace Dotenv.parse # TODO: detect true changes before processing block below (or yield)
+      @on_change_listeners.each_pair do |key, block|
+        old_value = nil # TODO: remember last previous value
+        new_value = method(key).call
+        block.call(new_value)
+      end
+    end
 
-      # TODO: replace with yield, thus externaliz process_block on behalf of HotEnv#initialize
-      process_block
+    def on_change(key, &block)
+      @on_change_listeners[key.downcase.to_sym] = block
     end
 
     private
@@ -37,10 +44,5 @@ module HotConstants
       else method(:load_string)
       end
     end
-
-    def process_block
-      ActiveRecord::Base.logger.level = log_active_record ? :debug : :fatal
-      ActionView::Base.logger.level = log_action_view ? :debug : :fatal
-    end
   end
 end