Remove ActiveRecord::Model

In the end I think the pain of implementing this seamlessly was not
worth the gain provided.

The intention was that it would allow plain ruby objects that might not
live in your main application to be subclassed and have persistence
mixed in. But I've decided that the benefit of doing that is not worth
the amount of complexity that the implementation introduced.

23 files changed, 186 insertions, 369 deletions

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 1675127ab0..45122539f1 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -43,7 +43,6 @@ module ActiveRecord
   autoload :Integration
   autoload :Migration
   autoload :Migrator, 'active_record/migration'
-  autoload :Model
   autoload :ModelSchema
   autoload :NestedAttributes
   autoload :Observer
diff --git a/activerecord/lib/active_record/associations/alias_tracker.rb b/activerecord/lib/active_record/associations/alias_tracker.rb
index 84540a7000..0c23029981 100644
--- a/activerecord/lib/active_record/associations/alias_tracker.rb
+++ b/activerecord/lib/active_record/associations/alias_tracker.rb
@@ -8,7 +8,7 @@ module ActiveRecord
       attr_reader :aliases, :table_joins, :connection
 
       # table_joins is an array of arel joins which might conflict with the aliases we assign here
-      def initialize(connection = ActiveRecord::Model.connection, table_joins = [])
+      def initialize(connection = Base.connection, table_joins = [])
         @aliases     = Hash.new { |h,k| h[k] = initial_count_for(k) }
         @table_joins = table_joins
         @connection  = connection
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 008696f6de..9a4fcdfda3 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -59,7 +59,7 @@ module ActiveRecord
           raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord"
         end
 
-        if [Base, Model].include?(active_record_super)
+        if superclass == Base
           super
         else
           # If B < A and A defines its own attribute method, then we don't want to overwrite that.
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index 59f209cec8..0333605eac 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -2,11 +2,6 @@ require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/deprecation'
 
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :partial_writes, instance_accessor: false
-    self.partial_writes = true
-  end
-
   module AttributeMethods
     module Dirty # :nodoc:
       extend ActiveSupport::Concern
@@ -18,7 +13,8 @@ module ActiveRecord
           raise "You cannot include Dirty after Timestamp"
         end
 
-        config_attribute :partial_writes
+        class_attribute :partial_writes, instance_writer: false
+        self.partial_writes = true
 
         def self.partial_updates=(v); self.partial_writes = v; end
         def self.partial_updates?; partial_writes?; end
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 46fd6ebfb3..07c8859496 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -1,8 +1,4 @@
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :attribute_types_cached_by_default, instance_accessor: false
-  end
-
   module AttributeMethods
     module Read
       extend ActiveSupport::Concern
@@ -10,7 +6,8 @@ module ActiveRecord
       ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
 
       included do
-        config_attribute :attribute_types_cached_by_default
+        class_attribute :attribute_types_cached_by_default, instance_writer: false
+        self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
       end
 
       module ClassMethods
@@ -79,8 +76,6 @@ module ActiveRecord
         end
       end
 
-      ActiveRecord::Model.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
-
       # Returns the value of the attribute identified by <tt>attr_name</tt> after
       # it has been typecast (for example, "2004-12-12" in a data column is cast
       # to a date object, like Date.new(2004, 12, 12)).
diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index f36a5806a9..806dc5b1d2 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -1,13 +1,4 @@
-
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :time_zone_aware_attributes, instance_accessor: false
-    self.time_zone_aware_attributes = false
-
-    mattr_accessor :skip_time_zone_conversion_for_attributes, instance_accessor: false
-    self.skip_time_zone_conversion_for_attributes = []
-  end
-
   module AttributeMethods
     module TimeZoneConversion
       class Type # :nodoc:
@@ -28,8 +19,11 @@ module ActiveRecord
       extend ActiveSupport::Concern
 
       included do
-        config_attribute :time_zone_aware_attributes, global: true
-        config_attribute :skip_time_zone_conversion_for_attributes
+        mattr_accessor :time_zone_aware_attributes, instance_writer: false
+        self.time_zone_aware_attributes = false
+
+        class_attribute :skip_time_zone_conversion_for_attributes, instance_writer: false
+        self.skip_time_zone_conversion_for_attributes = []
       end
 
       module ClassMethods
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index a4705b24ca..eabbd80f66 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -321,8 +321,48 @@ module ActiveRecord #:nodoc:
   # So it's possible to assign a logger to the class through <tt>Base.logger=</tt> which will then be used by all
   # instances in the current object space.
   class Base
-    include ActiveRecord::Model
+    extend ActiveModel::Observing::ClassMethods
+    extend ActiveModel::Naming
+
+    extend ActiveSupport::Benchmarkable
+    extend ActiveSupport::DescendantsTracker
+
+    extend ConnectionHandling
+    extend QueryCache::ClassMethods
+    extend Querying
+    extend Translation
+    extend DynamicMatchers
+    extend Explain
+    extend ConnectionHandling
+
+    include Persistence
+    include ReadonlyAttributes
+    include ModelSchema
+    include Inheritance
+    include Scoping
+    include Sanitization
+    include AttributeAssignment
+    include ActiveModel::Conversion
+    include Integration
+    include Validations
+    include CounterCache
+    include Locking::Optimistic
+    include Locking::Pessimistic
+    include AttributeMethods
+    include Callbacks
+    include ActiveModel::Observing
+    include Timestamp
+    include Associations
+    include ActiveModel::SecurePassword
+    include AutosaveAssociation
+    include NestedAttributes
+    include Aggregations
+    include Transactions
+    include Reflection
+    include Serialization
+    include Store
+    include Core
   end
-end
 
-ActiveSupport.run_load_hooks(:active_record, ActiveRecord::Model::DeprecationProxy.new)
+  ActiveSupport.run_load_hooks(:active_record, Base)
+end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 42bd16db80..1da95f451f 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -441,11 +441,11 @@ module ActiveRecord
       end
 
       def new_connection
-        ActiveRecord::Model.send(spec.adapter_method, spec.config)
+        Base.send(spec.adapter_method, spec.config)
       end
 
       def current_connection_id #:nodoc:
-        ActiveRecord::Model.connection_id ||= Thread.current.object_id
+        Base.connection_id ||= Thread.current.object_id
       end
 
       def checkout_new_connection
@@ -567,10 +567,10 @@ module ActiveRecord
         class_to_pool[klass] ||= begin
           until pool = pool_for(klass)
             klass = klass.superclass
-            break unless klass < ActiveRecord::Tag
+            break unless klass <= Base
           end
 
-          class_to_pool[klass] = pool || pool_for(ActiveRecord::Model)
+          class_to_pool[klass] = pool
         end
       end
 
diff --git a/activerecord/lib/active_record/connection_handling.rb b/activerecord/lib/active_record/connection_handling.rb
index 3531be05bf..8ce7a7a463 100644
--- a/activerecord/lib/active_record/connection_handling.rb
+++ b/activerecord/lib/active_record/connection_handling.rb
@@ -1,4 +1,3 @@
-
 module ActiveRecord
   module ConnectionHandling
     # Establishes the connection to the database. Accepts a hash as input where
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index f97c363871..b21765aa75 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -4,73 +4,6 @@ require 'thread'
 
 module ActiveRecord
   ActiveSupport.on_load(:active_record_config) do
-    ##
-    # :singleton-method:
-    #
-    # Accepts a logger conforming to the interface of Log4r which is then
-    # passed on to any new database connections made and which can be
-    # retrieved on both a class and instance level by calling +logger+.
-    mattr_accessor :logger, instance_accessor: false
-
-    ##
-    # :singleton-method:
-    # Contains the database configuration - as is typically stored in config/database.yml -
-    # as a Hash.
-    #
-    # For example, the following database.yml...
-    #
-    #   development:
-    #     adapter: sqlite3
-    #     database: db/development.sqlite3
-    #
-    #   production:
-    #     adapter: sqlite3
-    #     database: db/production.sqlite3
-    #
-    # ...would result in ActiveRecord::Base.configurations to look like this:
-    #
-    #   {
-    #      'development' => {
-    #         'adapter'  => 'sqlite3',
-    #         'database' => 'db/development.sqlite3'
-    #      },
-    #      'production' => {
-    #         'adapter'  => 'sqlite3',
-    #         'database' => 'db/production.sqlite3'
-    #      }
-    #   }
-    mattr_accessor :configurations, instance_accessor: false
-    self.configurations = {}
-
-    ##
-    # :singleton-method:
-    # Determines whether to use Time.utc (using :utc) or Time.local (using :local) when pulling
-    # dates and times from the database. This is set to :utc by default.
-    mattr_accessor :default_timezone, instance_accessor: false
-    self.default_timezone = :utc
-
-    ##
-    # :singleton-method:
-    # Specifies the format to use when dumping the database schema with Rails'
-    # Rakefile. If :sql, the schema is dumped as (potentially database-
-    # specific) SQL statements. If :ruby, the schema is dumped as an
-    # ActiveRecord::Schema file which can be loaded into any database that
-    # supports migrations. Use :ruby if you want to have different database
-    # adapters for, e.g., your development and test environments.
-    mattr_accessor :schema_format, instance_accessor: false
-    self.schema_format = :ruby
-
-    ##
-    # :singleton-method:
-    # Specify whether or not to use timestamps for migration versions
-    mattr_accessor :timestamped_migrations, instance_accessor: false
-    self.timestamped_migrations = true
-
-    mattr_accessor :connection_handler, instance_accessor: false
-    self.connection_handler = ConnectionAdapters::ConnectionHandler.new
-
-    mattr_accessor :dependent_restrict_raises, instance_accessor: false
-    self.dependent_restrict_raises = true
   end
 
   module Core
@@ -79,12 +12,71 @@ module ActiveRecord
     included do
       ##
       # :singleton-method:
-      # The connection handler
-      config_attribute :connection_handler
+      #
+      # Accepts a logger conforming to the interface of Log4r which is then
+      # passed on to any new database connections made and which can be
+      # retrieved on both a class and instance level by calling +logger+.
+      mattr_accessor :logger, instance_writer: false
 
-      %w(logger configurations default_timezone schema_format timestamped_migrations).each do |name|
-        config_attribute name, global: true
-      end
+      ##
+      # :singleton-method:
+      # Contains the database configuration - as is typically stored in config/database.yml -
+      # as a Hash.
+      #
+      # For example, the following database.yml...
+      #
+      #   development:
+      #     adapter: sqlite3
+      #     database: db/development.sqlite3
+      #
+      #   production:
+      #     adapter: sqlite3
+      #     database: db/production.sqlite3
+      #
+      # ...would result in ActiveRecord::Base.configurations to look like this:
+      #
+      #   {
+      #      'development' => {
+      #         'adapter'  => 'sqlite3',
+      #         'database' => 'db/development.sqlite3'
+      #      },
+      #      'production' => {
+      #         'adapter'  => 'sqlite3',
+      #         'database' => 'db/production.sqlite3'
+      #      }
+      #   }
+      mattr_accessor :configurations, instance_writer: false
+      self.configurations = {}
+
+      ##
+      # :singleton-method:
+      # Determines whether to use Time.utc (using :utc) or Time.local (using :local) when pulling
+      # dates and times from the database. This is set to :utc by default.
+      mattr_accessor :default_timezone, instance_writer: false
+      self.default_timezone = :utc
+
+      ##
+      # :singleton-method:
+      # Specifies the format to use when dumping the database schema with Rails'
+      # Rakefile. If :sql, the schema is dumped as (potentially database-
+      # specific) SQL statements. If :ruby, the schema is dumped as an
+      # ActiveRecord::Schema file which can be loaded into any database that
+      # supports migrations. Use :ruby if you want to have different database
+      # adapters for, e.g., your development and test environments.
+      mattr_accessor :schema_format, instance_writer: false
+      self.schema_format = :ruby
+
+      ##
+      # :singleton-method:
+      # Specify whether or not to use timestamps for migration versions
+      mattr_accessor :timestamped_migrations, instance_writer: false
+      self.timestamped_migrations = true
+
+      class_attribute :connection_handler, instance_writer: false
+      self.connection_handler = ConnectionAdapters::ConnectionHandler.new
+
+      mattr_accessor :dependent_restrict_raises, instance_writer: false
+      self.dependent_restrict_raises = true
     end
 
     module ClassMethods
@@ -139,7 +131,13 @@ module ActiveRecord
 
       # Returns the Arel engine.
       def arel_engine
-        @arel_engine ||= connection_handler.retrieve_connection_pool(self) ? self : active_record_super.arel_engine
+        @arel_engine ||= begin
+          if Base == self || connection_handler.retrieve_connection_pool(self)
+            self
+          else
+            superclass.arel_engine
+          end
+       end
       end
 
       private
diff --git a/activerecord/lib/active_record/explain.rb b/activerecord/lib/active_record/explain.rb
index 9e0390bed1..af772996f1 100644
--- a/activerecord/lib/active_record/explain.rb
+++ b/activerecord/lib/active_record/explain.rb
@@ -1,12 +1,10 @@
 require 'active_support/lazy_load_hooks'
 
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :auto_explain_threshold_in_seconds, instance_accessor: false
-  end
-
   module Explain
-    delegate :auto_explain_threshold_in_seconds, :auto_explain_threshold_in_seconds=, to: 'ActiveRecord::Model'
+    def self.extended(base)
+      base.mattr_accessor :auto_explain_threshold_in_seconds, instance_accessor: false
+    end
 
     # If auto explain is enabled, this method triggers EXPLAIN logging for the
     # queries triggered by the block if it takes more than the threshold as a
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 413bd147de..6bc5cd1fb9 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -553,7 +553,7 @@ module ActiveRecord
       rows[table_name] = fixtures.map do |label, fixture|
         row = fixture.to_hash
 
-        if model_class && model_class < ActiveRecord::Model
+        if model_class && model_class < ActiveRecord::Base
           # fill in timestamp columns if they aren't specified and the model is set to record_timestamps
           if model_class.record_timestamps
             timestamp_column_names.each do |c_name|
diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb
index 35273b0d81..a448fa1f5c 100644
--- a/activerecord/lib/active_record/inheritance.rb
+++ b/activerecord/lib/active_record/inheritance.rb
@@ -1,29 +1,22 @@
-
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    # Determine whether to store the full constant name including namespace when using STI
-    mattr_accessor :store_full_sti_class, instance_accessor: false
-    self.store_full_sti_class = true
-  end
-
   module Inheritance
     extend ActiveSupport::Concern
 
     included do
-      config_attribute :store_full_sti_class
+      # Determine whether to store the full constant name including namespace when using STI
+      class_attribute :store_full_sti_class, instance_writer: false
+      self.store_full_sti_class = true
     end
 
     module ClassMethods
       # True if this isn't a concrete subclass needing a STI type condition.
       def descends_from_active_record?
-        sup = active_record_super
-
-        if sup.abstract_class?
-          sup.descends_from_active_record?
-        elsif self == Base
+        if self == Base
           false
+        elsif superclass.abstract_class?
+          superclass.descends_from_active_record?
         else
-          [Base, Model].include?(sup) || !columns_hash.include?(inheritance_column)
+          superclass == Base || !columns_hash.include?(inheritance_column)
         end
       end
 
@@ -40,9 +33,8 @@ module ActiveRecord
         @symbolized_sti_name ||= sti_name.present? ? sti_name.to_sym : symbolized_base_class
       end
 
-      # Returns the class descending directly from ActiveRecord::Base (or
-      # that includes ActiveRecord::Model), or an  abstract class, if any, in
-      # the inheritance hierarchy.
+      # Returns the class descending directly from ActiveRecord::Base, or
+      # an abstract class, if any, in the inheritance hierarchy.
       #
       # If A extends AR::Base, A.base_class will return A. If B descends from A
       # through some arbitrarily deep hierarchy, B.base_class will return A.
@@ -50,15 +42,14 @@ module ActiveRecord
       # If B < A and C < B and if A is an abstract_class then both B.base_class
       # and C.base_class would return B as the answer since A is an abstract_class.
       def base_class
-        unless self < ActiveRecord::Tag
+        unless self < Base
           raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
         end
 
-        sup = active_record_super
-        if sup == Base || sup == Model || sup.abstract_class?
+        if superclass == Base || superclass.abstract_class?
           self
         else
-          sup.base_class
+          superclass.base_class
         end
       end
 
@@ -97,14 +88,6 @@ module ActiveRecord
         sti_class.allocate.init_with('attributes' => record, 'column_types' => column_types)
       end
 
-      # For internal use.
-      #
-      # If this class includes ActiveRecord::Model then it won't have a
-      # superclass. So this provides a way to get to the 'root' (ActiveRecord::Model).
-      def active_record_super #:nodoc:
-        superclass < Model ? superclass : Model
-      end
-
       protected
 
       # Returns the class type of the record using the current module as a prefix. So descendants of
diff --git a/activerecord/lib/active_record/locking/optimistic.rb b/activerecord/lib/active_record/locking/optimistic.rb
index e96ed00f9c..035c77c424 100644
--- a/activerecord/lib/active_record/locking/optimistic.rb
+++ b/activerecord/lib/active_record/locking/optimistic.rb
@@ -1,9 +1,4 @@
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :lock_optimistically, instance_accessor: false
-    self.lock_optimistically = true
-  end
-
   module Locking
     # == What is Optimistic Locking
     #
@@ -56,7 +51,8 @@ module ActiveRecord
       extend ActiveSupport::Concern
 
       included do
-        config_attribute :lock_optimistically
+        class_attribute :lock_optimistically, instance_writer: false
+        self.lock_optimistically = true
       end
 
       def locking_enabled? #:nodoc:
diff --git a/activerecord/lib/active_record/model.rb b/activerecord/lib/active_record/model.rb
deleted file mode 100644
index f059840f4d..0000000000
--- a/activerecord/lib/active_record/model.rb
+++ /dev/null
@@ -1,167 +0,0 @@
-require 'active_support/core_ext/module/attribute_accessors'
-
-module ActiveRecord
-  module Configuration # :nodoc:
-    # This just abstracts out how we define configuration options in AR. Essentially we
-    # have mattr_accessors on the ActiveRecord:Model constant that define global defaults.
-    # Classes that then use AR get class_attributes defined, which means that when they
-    # are assigned the default will be overridden for that class and subclasses. (Except
-    # when options[:global] == true, in which case there is one global value always.)
-    def config_attribute(name, options = {})
-      if options[:global]
-        class_eval <<-CODE, __FILE__, __LINE__ + 1
-          def self.#{name};       ActiveRecord::Model.#{name};       end
-          def #{name};            ActiveRecord::Model.#{name};       end
-          def self.#{name}=(val); ActiveRecord::Model.#{name} = val; end
-        CODE
-      else
-        options[:instance_writer] ||= false
-        class_attribute name, options
-
-        singleton_class.class_eval <<-CODE, __FILE__, __LINE__ + 1
-          remove_method :#{name}
-          def #{name}; ActiveRecord::Model.#{name}; end
-        CODE
-      end
-    end
-  end
-
-  # This allows us to detect an ActiveRecord::Model while it's in the process of
-  # being included.
-  module Tag; end
-
-  # <tt>ActiveRecord::Model</tt> can be included into a class to add Active Record
-  # persistence. This is an alternative to inheriting from <tt>ActiveRecord::Base</tt>.
-  #
-  #     class Post
-  #       include ActiveRecord::Model
-  #     end
-  module Model
-    extend ActiveSupport::Concern
-    extend ConnectionHandling
-    extend ActiveModel::Observing::ClassMethods
-
-    def self.append_features(base)
-      base.class_eval do
-        include Tag
-        extend Configuration
-      end
-
-      super
-    end
-
-    included do
-      extend ActiveModel::Naming
-      extend ActiveSupport::Benchmarkable
-      extend ActiveSupport::DescendantsTracker
-
-      extend QueryCache::ClassMethods
-      extend Querying
-      extend Translation
-      extend DynamicMatchers
-      extend Explain
-      extend ConnectionHandling
-
-      initialize_generated_modules unless self == Base
-    end
-
-    include Persistence
-    include ReadonlyAttributes
-    include ModelSchema
-    include Inheritance
-    include Scoping
-    include Sanitization
-    include AttributeAssignment
-    include ActiveModel::Conversion
-    include Integration
-    include Validations
-    include CounterCache
-    include Locking::Optimistic
-    include Locking::Pessimistic
-    include AttributeMethods
-    include Callbacks
-    include ActiveModel::Observing
-    include Timestamp
-    include Associations
-    include ActiveModel::SecurePassword
-    include AutosaveAssociation
-    include NestedAttributes
-    include Aggregations
-    include Transactions
-    include Reflection
-    include Serialization
-    include Store
-    include Core
-
-    class << self
-      def arel_engine
-        self
-      end
-
-      def abstract_class?
-        false
-      end
-
-      # Defines the name of the table column which will store the class name on single-table
-      # inheritance situations.
-      #
-      # The default inheritance column name is +type+, which means it's a
-      # reserved word inside Active Record. To be able to use single-table
-      # inheritance with another column name, or to use the column +type+ in
-      # your own model for something else, you can set +inheritance_column+:
-      #
-      #     self.inheritance_column = 'zoink'
-      def inheritance_column
-        'type'
-      end
-    end
-
-    class DeprecationProxy < BasicObject #:nodoc:
-      def initialize(model = Model, base = Base)
-        @model = model
-        @base  = base
-      end
-
-      def method_missing(name, *args, &block)
-        if @model.respond_to?(name, true)
-          @model.send(name, *args, &block)
-        else
-          ::ActiveSupport::Deprecation.warn(
-            "The object passed to the active_record load hook was previously ActiveRecord::Base " \
-            "(a Class). Now it is ActiveRecord::Model (a Module). You have called `#{name}' which " \
-            "is only defined on ActiveRecord::Base. Please change your code so that it works with " \
-            "a module rather than a class. (Model is included in Base, so anything added to Model " \
-            "will be available on Base as well.)"
-          )
-          @base.send(name, *args, &block)
-        end
-      end
-
-      alias send method_missing
-
-      def extend(*mods)
-        ::ActiveSupport::Deprecation.warn(
-          "The object passed to the active_record load hook was previously ActiveRecord::Base " \
-          "(a Class). Now it is ActiveRecord::Model (a Module). You have called `extend' which " \
-          "would add singleton methods to Model. This is presumably not what you want, since the " \
-          "methods would not be inherited down to Base. Rather than using extend, please use " \
-          "ActiveSupport::Concern + include, which will ensure that your class methods are " \
-          "inherited."
-        )
-        @base.extend(*mods)
-      end
-    end
-  end
-
-  # This hook is where config accessors on Model get defined.
-  #
-  # We don't want to just open the Model module and add stuff to it in other files, because
-  # that would cause Model to load, which causes all sorts of loading order issues.
-  #
-  # We need this hook rather than just using the :active_record one, because users of the
-  # :active_record hook may need to use config options.
-  ActiveSupport.run_load_hooks(:active_record_config, Model)
-
-  # Load Base at this point, because the active_record load hook is run in that file.
-  Base
-end
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 99de16cd33..1b95b72c8a 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -1,18 +1,4 @@
-
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :primary_key_prefix_type, instance_accessor: false
-
-    mattr_accessor :table_name_prefix, instance_accessor: false
-    self.table_name_prefix = ""
-
-    mattr_accessor :table_name_suffix, instance_accessor: false
-    self.table_name_suffix = ""
-
-    mattr_accessor :pluralize_table_names, instance_accessor: false
-    self.pluralize_table_names = true
-  end
-
   module ModelSchema
     extend ActiveSupport::Concern
 
@@ -24,7 +10,7 @@ module ActiveRecord
       # the Product class will look for "productid" instead of "id" as the primary column. If the
       # latter is specified, the Product class will look for "product_id" instead of "id". Remember
       # that this is a global setting for all Active Records.
-      config_attribute :primary_key_prefix_type, global: true
+      mattr_accessor :primary_key_prefix_type, instance_writer: false
 
       ##
       # :singleton-method:
@@ -36,20 +22,25 @@ module ActiveRecord
       # If you are organising your models within modules you can add a prefix to the models within
       # a namespace by defining a singleton method in the parent module called table_name_prefix which
       # returns your chosen prefix.
-      config_attribute :table_name_prefix
+      class_attribute :table_name_prefix, instance_writer: false
+      self.table_name_prefix = ""
 
       ##
       # :singleton-method:
       # Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp",
       # "people_basecamp"). By default, the suffix is the empty string.
-      config_attribute :table_name_suffix
+      class_attribute :table_name_suffix, instance_writer: false
+      self.table_name_suffix = ""
 
       ##
       # :singleton-method:
       # Indicates whether table names should be the pluralized versions of the corresponding class names.
       # If true, the default table name for a Product class will be +products+. If false, it would just be +product+.
       # See table_name for the full rules on table/class naming. This is true, by default.
-      config_attribute :pluralize_table_names
+      class_attribute :pluralize_table_names, instance_writer: false
+      self.pluralize_table_names = true
+
+      self.inheritance_column = 'type'
     end
 
     module ClassMethods
@@ -144,9 +135,9 @@ module ActiveRecord
       # Computes the table name, (re)sets it internally, and returns it.
       def reset_table_name #:nodoc:
         self.table_name = if abstract_class?
-          active_record_super == Base ? nil : active_record_super.table_name
-        elsif active_record_super.abstract_class?
-          active_record_super.table_name || compute_table_name
+          superclass == Base ? nil : superclass.table_name
+        elsif superclass.abstract_class?
+          superclass.table_name || compute_table_name
         else
           compute_table_name
         end
@@ -156,9 +147,17 @@ module ActiveRecord
         (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
       end
 
-      # The name of the column containing the object's class when Single Table Inheritance is used
+      # Defines the name of the table column which will store the class name on single-table
+      # inheritance situations.
+      #
+      # The default inheritance column name is +type+, which means it's a
+      # reserved word inside Active Record. To be able to use single-table
+      # inheritance with another column name, or to use the column +type+ in
+      # your own model for something else, you can set +inheritance_column+:
+      #
+      #     self.inheritance_column = 'zoink'
       def inheritance_column
-        (@inheritance_column ||= nil) || active_record_super.inheritance_column
+        (@inheritance_column ||= nil) || superclass.inheritance_column
       end
 
       # Sets the value of inheritance_column
@@ -331,7 +330,7 @@ module ActiveRecord
         base = base_class
         if self == base
           # Nested classes are prefixed with singular parent table name.
-          if parent < ActiveRecord::Model && !parent.abstract_class?
+          if parent < Base && !parent.abstract_class?
             contained = parent.table_name
             contained = contained.singularize if parent.pluralize_table_names
             contained += '_'
diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb
index 2e7fb3bbb3..d026c50ee6 100644
--- a/activerecord/lib/active_record/nested_attributes.rb
+++ b/activerecord/lib/active_record/nested_attributes.rb
@@ -3,11 +3,6 @@ require 'active_support/core_ext/object/try'
 require 'active_support/core_ext/hash/indifferent_access'
 
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :nested_attributes_options, instance_accessor: false
-    self.nested_attributes_options = {}
-  end
-
   module NestedAttributes #:nodoc:
     class TooManyRecords < ActiveRecordError
     end
@@ -15,7 +10,8 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     included do
-      config_attribute :nested_attributes_options
+      class_attribute :nested_attributes_options, instance_writer: false
+      self.nested_attributes_options = {}
     end
 
     # = Active Record Nested Attributes
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index d7e35fb771..77e41ea927 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -80,7 +80,7 @@ module ActiveRecord
             if File.file?(filename)
               cache = Marshal.load File.binread filename
               if cache.version == ActiveRecord::Migrator.current_version
-                ActiveRecord::Model.connection.schema_cache = cache
+                self.connection.schema_cache = cache
               else
                 warn "Ignoring db/schema_cache.dump because it has expired. The current schema version is #{ActiveRecord::Migrator.current_version}, but the one in the cache is #{cache.version}."
               end
@@ -122,8 +122,8 @@ module ActiveRecord
 
       ActiveSupport.on_load(:active_record) do
         ActionDispatch::Reloader.send(hook) do
-          ActiveRecord::Model.clear_reloadable_connections!
-          ActiveRecord::Model.clear_cache!
+          ActiveRecord::Base.clear_reloadable_connections!
+          ActiveRecord::Base.clear_cache!
         end
       end
     end
@@ -135,13 +135,12 @@ module ActiveRecord
 
     config.after_initialize do |app|
       ActiveSupport.on_load(:active_record) do
-        ActiveRecord::Model.instantiate_observers
+        instantiate_observers
 
         ActionDispatch::Reloader.to_prepare do
-          ActiveRecord::Model.instantiate_observers
+          ActiveRecord::Base.instantiate_observers
         end
       end
-
     end
   end
 end
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 84aaa39fed..99c2f45bc8 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -159,7 +159,7 @@ module ActiveRecord
     #   Person.exists?(false)
     #   Person.exists?
     def exists?(conditions = :none)
-      conditions = conditions.id if ActiveRecord::Model === conditions
+      conditions = conditions.id if Base === conditions
       return false if !conditions
 
       join_dependency = construct_join_dependency_for_association_find
diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index 71030cb5d7..bd7aeb0c4e 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -40,7 +40,7 @@ module ActiveRecord
       #
       # For polymorphic relationships, find the foreign key and type:
       # PriceEstimate.where(:estimate_of => treasure)
-      if klass && value.class < ActiveRecord::Tag && reflection = klass.reflect_on_association(column.to_sym)
+      if klass && value.class < Base && reflection = klass.reflect_on_association(column.to_sym)
         if reflection.polymorphic?
           queries << build(table[reflection.foreign_type], value.class.base_class)
         end
@@ -67,7 +67,7 @@ module ActiveRecord
       def self.build(attribute, value)
         case value
         when Array, ActiveRecord::Associations::CollectionProxy
-          values = value.to_a.map {|x| x.is_a?(ActiveRecord::Model) ? x.id : x}
+          values = value.to_a.map {|x| x.is_a?(Base) ? x.id : x}
           ranges, values = values.partition {|v| v.is_a?(Range)}
 
           values_predicate = if values.include?(nil)
@@ -93,7 +93,7 @@ module ActiveRecord
           attribute.in(value.arel.ast)
         when Range
           attribute.in(value)
-        when ActiveRecord::Model
+        when ActiveRecord::Base
           attribute.eq(value.id)
         when Class
           # FIXME: I think we need to deprecate this behavior
diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index 425b9b41d8..bea195e9b8 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -56,7 +56,7 @@ module ActiveRecord
       @hash_rows ||=
         begin
           # We freeze the strings to prevent them getting duped when
-          # used as keys in ActiveRecord::Model's @attributes hash
+          # used as keys in ActiveRecord::Base's @attributes hash
           columns = @columns.map { |c| c.dup.freeze }
           @rows.map { |row|
             Hash[columns.zip(row)]
diff --git a/activerecord/lib/active_record/serialization.rb b/activerecord/lib/active_record/serialization.rb
index e8dd312a47..6a511c307b 100644
--- a/activerecord/lib/active_record/serialization.rb
+++ b/activerecord/lib/active_record/serialization.rb
@@ -1,19 +1,12 @@
 module ActiveRecord #:nodoc:
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :include_root_in_json, instance_accessor: false
-    self.include_root_in_json = true
-  end
-
   # = Active Record Serialization
   module Serialization
     extend ActiveSupport::Concern
     include ActiveModel::Serializers::JSON
 
     included do
-      singleton_class.class_eval do
-        remove_method :include_root_in_json
-        delegate :include_root_in_json, to: 'ActiveRecord::Model'
-      end
+      mattr_accessor :include_root_in_json, instance_accessor: false
+      self.include_root_in_json = true
     end
 
     def serializable_hash(options = nil)
diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index ec4588f601..920d6848c1 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -1,8 +1,6 @@
 
 module ActiveRecord
   ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :record_timestamps, instance_accessor: false
-    self.record_timestamps = true
   end
 
   # = Active Record Timestamp
@@ -37,7 +35,8 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     included do
-      config_attribute :record_timestamps, instance_writer: true
+      class_attribute :record_timestamps
+      self.record_timestamps = true
     end
 
     def initialize_dup(other) # :nodoc: