Use a deliberately-invalid migration version in all doc examples

If we use a real version, at best that'll be an onerous update required
for each release; at worst, it will encourage users to write new
migrations against an older version than they're using.

The other option would be to leave these bare, without any version
specifier. But as that's just a variant spelling of "4.2", it would seem
to raise the same concerns as above.

9 files changed, 54 insertions, 54 deletions

diff --git a/activerecord/README.rdoc b/activerecord/README.rdoc
index 7eb4e9db1a..9c37b97f76 100644
--- a/activerecord/README.rdoc
+++ b/activerecord/README.rdoc
@@ -138,7 +138,7 @@ This would also define the following accessors: <tt>Product#name</tt> and
 
 * Database agnostic schema management with Migrations.
 
-    class AddSystemSettings < ActiveRecord::Migration
+    class AddSystemSettings < ActiveRecord::Migration[0.0]
       def up
         create_table :system_settings do |t|
           t.string  :name
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index b806a2f832..f2a637e727 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1639,7 +1639,7 @@ module ActiveRecord
       # The join table should not have a primary key or a model associated with it. You must manually generate the
       # join table with a migration such as this:
       #
-      #   class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration
+      #   class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration[0.0]
       #     def change
       #       create_join_table :developers, :projects
       #     end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 159cbcb85a..9ec8e0fc26 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -190,7 +190,7 @@ module ActiveRecord
     # Inside migration files, the +t+ object in {create_table}[rdoc-ref:SchemaStatements#create_table]
     # is actually of this type:
     #
-    #   class SomeMigration < ActiveRecord::Migration
+    #   class SomeMigration < ActiveRecord::Migration[0.0]
     #     def up
     #       create_table :foo do |t|
     #         puts t.class  # => "ActiveRecord::ConnectionAdapters::TableDefinition"
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 53a84c1342..b2418e4247 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -13,7 +13,7 @@ module ActiveRecord
   # For example the following migration is not reversible.
   # Rolling back this migration will raise an ActiveRecord::IrreversibleMigration error.
   #
-  #   class IrreversibleMigrationExample < ActiveRecord::Migration
+  #   class IrreversibleMigrationExample < ActiveRecord::Migration[0.0]
   #     def change
   #       create_table :distributors do |t|
   #         t.string :zipcode
@@ -31,7 +31,7 @@ module ActiveRecord
   #
   # 1. Define <tt>#up</tt> and <tt>#down</tt> methods instead of <tt>#change</tt>:
   #
-  #  class ReversibleMigrationExample < ActiveRecord::Migration
+  #  class ReversibleMigrationExample < ActiveRecord::Migration[0.0]
   #    def up
   #      create_table :distributors do |t|
   #        t.string :zipcode
@@ -56,7 +56,7 @@ module ActiveRecord
   #
   # 2. Use the #reversible method in <tt>#change</tt> method:
   #
-  #   class ReversibleMigrationExample < ActiveRecord::Migration
+  #   class ReversibleMigrationExample < ActiveRecord::Migration[0.0]
   #     def change
   #       create_table :distributors do |t|
   #         t.string :zipcode
@@ -155,7 +155,7 @@ module ActiveRecord
   #
   # Example of a simple migration:
   #
-  #   class AddSsl < ActiveRecord::Migration
+  #   class AddSsl < ActiveRecord::Migration[0.0]
   #     def up
   #       add_column :accounts, :ssl_enabled, :boolean, default: true
   #     end
@@ -175,7 +175,7 @@ module ActiveRecord
   #
   # Example of a more complex migration that also needs to initialize data:
   #
-  #   class AddSystemSettings < ActiveRecord::Migration
+  #   class AddSystemSettings < ActiveRecord::Migration[0.0]
   #     def up
   #       create_table :system_settings do |t|
   #         t.string  :name
@@ -301,7 +301,7 @@ module ActiveRecord
   #   rails generate migration add_fieldname_to_tablename fieldname:string
   #
   # This will generate the file <tt>timestamp_add_fieldname_to_tablename.rb</tt>, which will look like this:
-  #   class AddFieldnameToTablename < ActiveRecord::Migration
+  #   class AddFieldnameToTablename < ActiveRecord::Migration[0.0]
   #     def change
   #       add_column :tablenames, :fieldname, :string
   #     end
@@ -332,7 +332,7 @@ module ActiveRecord
   #
   # Not all migrations change the schema. Some just fix the data:
   #
-  #   class RemoveEmptyTags < ActiveRecord::Migration
+  #   class RemoveEmptyTags < ActiveRecord::Migration[0.0]
   #     def up
   #       Tag.all.each { |tag| tag.destroy if tag.pages.empty? }
   #     end
@@ -345,7 +345,7 @@ module ActiveRecord
   #
   # Others remove columns when they migrate up instead of down:
   #
-  #   class RemoveUnnecessaryItemAttributes < ActiveRecord::Migration
+  #   class RemoveUnnecessaryItemAttributes < ActiveRecord::Migration[0.0]
   #     def up
   #       remove_column :items, :incomplete_items_count
   #       remove_column :items, :completed_items_count
@@ -359,7 +359,7 @@ module ActiveRecord
   #
   # And sometimes you need to do something in SQL not abstracted directly by migrations:
   #
-  #   class MakeJoinUnique < ActiveRecord::Migration
+  #   class MakeJoinUnique < ActiveRecord::Migration[0.0]
   #     def up
   #       execute "ALTER TABLE `pages_linked_pages` ADD UNIQUE `page_id_linked_page_id` (`page_id`,`linked_page_id`)"
   #     end
@@ -376,7 +376,7 @@ module ActiveRecord
   # <tt>Base#reset_column_information</tt> in order to ensure that the model has the
   # latest column data from after the new column was added. Example:
   #
-  #   class AddPeopleSalary < ActiveRecord::Migration
+  #   class AddPeopleSalary < ActiveRecord::Migration[0.0]
   #     def up
   #       add_column :people, :salary, :integer
   #       Person.reset_column_information
@@ -434,7 +434,7 @@ module ActiveRecord
   # To define a reversible migration, define the +change+ method in your
   # migration like this:
   #
-  #   class TenderloveMigration < ActiveRecord::Migration
+  #   class TenderloveMigration < ActiveRecord::Migration[0.0]
   #     def change
   #       create_table(:horses) do |t|
   #         t.column :content, :text
@@ -464,7 +464,7 @@ module ActiveRecord
   # can't execute inside a transaction though, and for these situations
   # you can turn the automatic transactions off.
   #
-  #   class ChangeEnum < ActiveRecord::Migration
+  #   class ChangeEnum < ActiveRecord::Migration[0.0]
   #     disable_ddl_transaction!
   #
   #     def up
@@ -601,7 +601,7 @@ module ActiveRecord
     # and create the table 'apples' on the way up, and the reverse
     # on the way down.
     #
-    #   class FixTLMigration < ActiveRecord::Migration
+    #   class FixTLMigration < ActiveRecord::Migration[0.0]
     #     def change
     #       revert do
     #         create_table(:horses) do |t|
@@ -620,7 +620,7 @@ module ActiveRecord
     #
     #   require_relative '20121212123456_tenderlove_migration'
     #
-    #   class FixupTLMigration < ActiveRecord::Migration
+    #   class FixupTLMigration < ActiveRecord::Migration[0.0]
     #     def change
     #       revert TenderloveMigration
     #
@@ -673,7 +673,7 @@ module ActiveRecord
     # when the three columns 'first_name', 'last_name' and 'full_name' exist,
     # even when migrating down:
     #
-    #    class SplitNameMigration < ActiveRecord::Migration
+    #    class SplitNameMigration < ActiveRecord::Migration[0.0]
     #      def change
     #        add_column :users, :first_name, :string
     #        add_column :users, :last_name, :string
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index e3f304b0af..8ae2a61aa8 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -275,7 +275,7 @@ module ActiveRecord
       # when just after creating a table you want to populate it with some default
       # values, eg:
       #
-      #  class CreateJobLevels < ActiveRecord::Migration
+      #  class CreateJobLevels < ActiveRecord::Migration[0.0]
       #    def up
       #      create_table :job_levels do |t|
       #        t.integer :id
diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md
index dafbe17bbd..db7bd49ee7 100644
--- a/guides/source/active_record_basics.md
+++ b/guides/source/active_record_basics.md
@@ -350,7 +350,7 @@ database that Active Record supports using `rake`. Here's a migration that
 creates a table:
 
 ```ruby
-class CreatePublications < ActiveRecord::Migration
+class CreatePublications < ActiveRecord::Migration[0.0]
   def change
     create_table :publications do |t|
       t.string :title
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md
index 5aa5dc4f60..b9bb051e7e 100644
--- a/guides/source/active_record_migrations.md
+++ b/guides/source/active_record_migrations.md
@@ -35,7 +35,7 @@ history to the latest version. Active Record will also update your
 Here's an example of a migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -72,7 +72,7 @@ If you wish for a migration to do something that Active Record doesn't know how
 to reverse, you can use `reversible`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration
+class ChangeProductsPrice < ActiveRecord::Migration[0.0]
   def change
     reversible do |dir|
       change_table :products do |t|
@@ -87,7 +87,7 @@ end
 Alternatively, you can use `up` and `down` instead of `change`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration
+class ChangeProductsPrice < ActiveRecord::Migration[0.0]
   def up
     change_table :products do |t|
       t.change :price, :string
@@ -129,7 +129,7 @@ $ bin/rails generate migration AddPartNumberToProducts
 This will create an empty but appropriately named migration:
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
   end
 end
@@ -146,7 +146,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string
 will generate
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
   end
@@ -162,7 +162,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string:index
 will generate
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
     add_index :products, :part_number
@@ -180,7 +180,7 @@ $ bin/rails generate migration RemovePartNumberFromProducts part_number:string
 generates
 
 ```ruby
-class RemovePartNumberFromProducts < ActiveRecord::Migration
+class RemovePartNumberFromProducts < ActiveRecord::Migration[0.0]
   def change
     remove_column :products, :part_number, :string
   end
@@ -196,7 +196,7 @@ $ bin/rails generate migration AddDetailsToProducts part_number:string price:dec
 generates
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration
+class AddDetailsToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
     add_column :products, :price, :decimal
@@ -215,7 +215,7 @@ $ bin/rails generate migration CreateProducts name:string part_number:string
 generates
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -239,7 +239,7 @@ $ bin/rails generate migration AddUserRefToProducts user:references
 generates
 
 ```ruby
-class AddUserRefToProducts < ActiveRecord::Migration
+class AddUserRefToProducts < ActiveRecord::Migration[0.0]
   def change
     add_reference :products, :user, index: true, foreign_key: true
   end
@@ -257,7 +257,7 @@ $ bin/rails g migration CreateJoinTableCustomerProduct customer product
 will produce the following migration:
 
 ```ruby
-class CreateJoinTableCustomerProduct < ActiveRecord::Migration
+class CreateJoinTableCustomerProduct < ActiveRecord::Migration[0.0]
   def change
     create_join_table :customers, :products do |t|
       # t.index [:customer_id, :product_id]
@@ -281,7 +281,7 @@ $ bin/rails generate model Product name:string description:text
 will create a migration that looks like this
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -309,7 +309,7 @@ $ bin/rails generate migration AddDetailsToProducts 'price:decimal{5,2}' supplie
 will produce a migration that looks like this
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration
+class AddDetailsToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :price, :decimal, precision: 5, scale: 2
     add_reference :products, :supplier, polymorphic: true, index: true
@@ -563,7 +563,7 @@ to reverse. You can use `reversible` to specify what to do when running a
 migration and what else to do when reverting it. For example:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration
+class ExampleMigration < ActiveRecord::Migration[0.0]
   def change
     create_table :distributors do |t|
       t.string :zipcode
@@ -616,7 +616,7 @@ is wise to perform the transformations in precisely the reverse order they were
 made in the `up` method. The example in the `reversible` section is equivalent to:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration
+class ExampleMigration < ActiveRecord::Migration[0.0]
   def up
     create_table :distributors do |t|
       t.string :zipcode
@@ -659,7 +659,7 @@ You can use Active Record's ability to rollback migrations using the `revert` me
 ```ruby
 require_relative '20121212123456_example_migration'
 
-class FixupExampleMigration < ActiveRecord::Migration
+class FixupExampleMigration < ActiveRecord::Migration[0.0]
   def change
     revert ExampleMigration
 
@@ -677,7 +677,7 @@ is later decided it would be best to use Active Record validations,
 in place of the `CHECK` constraint, to verify the zipcode.
 
 ```ruby
-class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration
+class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration[0.0]
   def change
     revert do
       # copy-pasted code from ExampleMigration
@@ -841,7 +841,7 @@ Several methods are provided in migrations that allow you to control all this:
 For example, this migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     suppress_messages do
       create_table :products do |t|
@@ -1015,7 +1015,7 @@ to add or modify data. This is useful in an existing database that can't be dest
 and recreated, such as a production database. 
 
 ```ruby
-class AddInitialProducts < ActiveRecord::Migration
+class AddInitialProducts < ActiveRecord::Migration[0.0]
   def up
     5.times do |i|
       Product.create(name: "Product ##{i}", description: "A product.")
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index c272daac28..1909e875ce 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -101,7 +101,7 @@ NOTE: `belongs_to` associations _must_ use the singular term. If you used the pl
 The corresponding migration might look like this:
 
 ```ruby
-class CreateOrders < ActiveRecord::Migration
+class CreateOrders < ActiveRecord::Migration[0.0]
   def change
     create_table :customers do |t|
       t.string :name
@@ -132,7 +132,7 @@ end
 The corresponding migration might look like this:
 
 ```ruby
-class CreateSuppliers < ActiveRecord::Migration
+class CreateSuppliers < ActiveRecord::Migration[0.0]
   def change
     create_table :suppliers do |t|
       t.string :name
@@ -176,7 +176,7 @@ NOTE: The name of the other model is pluralized when declaring a `has_many` asso
 The corresponding migration might look like this:
 
 ```ruby
-class CreateCustomers < ActiveRecord::Migration
+class CreateCustomers < ActiveRecord::Migration[0.0]
   def change
     create_table :customers do |t|
       t.string :name
@@ -218,7 +218,7 @@ end
 The corresponding migration might look like this:
 
 ```ruby
-class CreateAppointments < ActiveRecord::Migration
+class CreateAppointments < ActiveRecord::Migration[0.0]
   def change
     create_table :physicians do |t|
       t.string :name
@@ -304,7 +304,7 @@ end
 The corresponding migration might look like this:
 
 ```ruby
-class CreateAccountHistories < ActiveRecord::Migration
+class CreateAccountHistories < ActiveRecord::Migration[0.0]
   def change
     create_table :suppliers do |t|
       t.string :name
@@ -345,7 +345,7 @@ end
 The corresponding migration might look like this:
 
 ```ruby
-class CreateAssembliesAndParts < ActiveRecord::Migration
+class CreateAssembliesAndParts < ActiveRecord::Migration[0.0]
   def change
     create_table :assemblies do |t|
       t.string :name
@@ -384,7 +384,7 @@ end
 The corresponding migration might look like this:
 
 ```ruby
-class CreateSuppliers < ActiveRecord::Migration
+class CreateSuppliers < ActiveRecord::Migration[0.0]
   def change
     create_table :suppliers do |t|
       t.string  :name
@@ -466,7 +466,7 @@ Similarly, you can retrieve `@product.pictures`.
 If you have an instance of the `Picture` model, you can get to its parent via `@picture.imageable`. To make this work, you need to declare both a foreign key column and a type column in the model that declares the polymorphic interface:
 
 ```ruby
-class CreatePictures < ActiveRecord::Migration
+class CreatePictures < ActiveRecord::Migration[0.0]
   def change
     create_table :pictures do |t|
       t.string  :name
@@ -483,7 +483,7 @@ end
 This migration can be simplified by using the `t.references` form:
 
 ```ruby
-class CreatePictures < ActiveRecord::Migration
+class CreatePictures < ActiveRecord::Migration[0.0]
   def change
     create_table :pictures do |t|
       t.string :name
@@ -514,7 +514,7 @@ With this setup, you can retrieve `@employee.subordinates` and `@employee.manage
 In your migrations/schema, you will add a references column to the model itself.
 
 ```ruby
-class CreateEmployees < ActiveRecord::Migration
+class CreateEmployees < ActiveRecord::Migration[0.0]
   def change
     create_table :employees do |t|
       t.references :manager, index: true
@@ -575,7 +575,7 @@ end
 This declaration needs to be backed up by the proper foreign key declaration on the orders table:
 
 ```ruby
-class CreateOrders < ActiveRecord::Migration
+class CreateOrders < ActiveRecord::Migration[0.0]
   def change
     create_table :orders do |t|
       t.datetime :order_date
@@ -611,7 +611,7 @@ end
 These need to be backed up by a migration to create the `assemblies_parts` table. This table should be created without a primary key:
 
 ```ruby
-class CreateAssembliesPartsJoinTable < ActiveRecord::Migration
+class CreateAssembliesPartsJoinTable < ActiveRecord::Migration[0.0]
   def change
     create_table :assemblies_parts, id: false do |t|
       t.integer :assembly_id
@@ -629,7 +629,7 @@ We pass `id: false` to `create_table` because that table does not represent a mo
 You can also use the method `create_join_table`
 
 ```ruby
-class CreateAssembliesPartsJoinTable < ActiveRecord::Migration
+class CreateAssembliesPartsJoinTable < ActiveRecord::Migration[0.0]
   def change
     create_join_table :assemblies, :parts do |t|
       t.index :assembly_id
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index 5700e71103..6cf43f496b 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -679,7 +679,7 @@ If you look in the `db/migrate/YYYYMMDDHHMMSS_create_articles.rb` file
 (remember, yours will have a slightly different name), here's what you'll find:
 
 ```ruby
-class CreateArticles < ActiveRecord::Migration
+class CreateArticles < ActiveRecord::Migration[0.0]
   def change
     create_table :articles do |t|
       t.string :title
@@ -1542,7 +1542,7 @@ In addition to the model, Rails has also made a migration to create the
 corresponding database table:
 
 ```ruby
-class CreateComments < ActiveRecord::Migration
+class CreateComments < ActiveRecord::Migration[0.0]
   def change
     create_table :comments do |t|
       t.string :commenter