Fixed #14455 -- Documented the backwards compatibility policy for local flavors. Implemented the policy for the changes in the Indonesian local flavor (from r14195) that stimulated the development of this policy. Thanks to Karen, Alex, Ramiro and Chris for their help developing the policy.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14411 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/localflavor/id/id_choices.py

@@ -1,3 +1,4 @@
+import warnings
 from django.utils.translation import ugettext_lazy as _
 
 # Reference: http://id.wikipedia.org/wiki/Daftar_provinsi_Indonesia
@@ -5,6 +6,11 @@ from django.utils.translation import ugettext_lazy as _
 # Indonesia does not have an official Province code standard.
 # I decided to use unambiguous and consistent (some are common) 3-letter codes.
 
+warnings.warn(
+    'There have been recent changes to the ID localflavor. See the release notes for details',
+    RuntimeWarning
+)
+
 PROVINCE_CHOICES = (
     ('ACE', _('Aceh')),
     ('BLI', _('Bali')),

docs/misc/api-stability.txt

@@ -150,3 +150,57 @@ Certain APIs are explicitly marked as "internal" in a couple of ways:
       (``_``). This is the standard Python way of indicating that something is
       private; if any method starts with a single ``_``, it's an internal API.
 
+.. _misc-api-stability-localflavor:
+
+Local flavors
+-------------
+
+.. versionchanged:: 1.3
+
+:mod:`django.contrib.localflavor` contains assorted pieces of code
+that are useful for particular countries or cultures. This data is
+local in nature, and is subject to change on timelines that will
+almost never correlate with Django's own release schedules. For
+example, a common change is to split a province into two new
+provinces, or to rename an existing province.
+
+These changes present two competing compatibility issues. Moving
+forward, displaying the names of deprecated, renamed and dissolved
+provinces in a selection widget is bad from a user interface
+perspective. However, maintaining full backwards compatibility
+requires that we support historical values that may be stored in a
+database -- including values that may no longer be valid.
+
+Therefore, Django has the following policy with respect to changes in
+local flavor:
+
+    * At the time of a Django release, the data and algorithms
+      contained in :mod:`django.contrib.localflavor` will, to the best
+      of our ability, reflect the officially gazetted policies of the
+      appropriate local government authority. If a province has been
+      added, altered, or removed, that change will be reflected in
+      Django's localflavor.
+
+    * These changes will *not* be backported to the previous stable
+      release. Upgrading a minor version of Django should not require
+      any data migration or audits for UI changes; therefore, if you
+      want to get the latest province list, you will either need to
+      upgrade your Django install, or backport the province list you
+      need.
+
+    * For one release, the affected localflavor module will raise a
+      ``RuntimeWarning`` when it is imported.
+
+    * The change will be announced in the release notes as a backwards
+      incompatible change requiring attention. The change will also be
+      annotated in the documentation for the localflavor module.
+
+    * Where necessary and feasible, a migration script will be provided
+      to aid the migration process.
+
+For example, Django 1.2 contains an Indonesian localflavor. It has a
+province list that includes "Nanggroe Aceh Darussalam (NAD)" as a
+province. The Indonesian government has changed the official name of
+the province to "Aceh (ACE)". As a result, Django 1.3 does *not*
+contain "Nanggroe Aceh Darussalam (NAD)" in the province list, but
+*does* contain "Aceh (ACE)".

docs/ref/contrib/localflavor.txt

@@ -129,6 +129,35 @@ in the file. See any of the existing flavors for examples.
 
 .. _create a ticket: http://code.djangoproject.com/simpleticket
 
+Localflavor and backwards compatibility
+=======================================
+
+As documented in our :ref:`API stability
+<misc-api-stability-localflavor>` policy, Django will always attempt
+to make :mod:`django.contrib.localflavor` reflect the officially
+gazetted policies of the appropriate local government authority. For
+example, if a government body makes a change to add, alter, or remove
+a province (or state, or county), that change will be reflected in
+Django's localflavor in the next stable Django release.
+
+When a backwards-incompatible change is made (for example, the removal
+or renaming of a province) the localflavor in question will raise a
+warning when that localflavor is imported. This provides a runtime
+indication that something may require attention.
+
+However, once you have addressed the backwards compatibility (for
+example, auditing your code to see if any data migration is required),
+the warning serves no purpose. The warning can then be supressed.
+For example, to suppress the warnings raised by the Indonesian
+localflavor you would use the following code::
+
+    import warnings
+    warnings.filterwarnings('ignore',
+                            category=RuntimeWarning,
+                            module='django.contrib.localflavor.id')
+    from django.contrib.localflavor.id import forms as id_forms
+
+
 Argentina (``ar``)
 =============================================
 
@@ -443,6 +472,11 @@ Indonesia (``id``)
 
     A ``Select`` widget that uses a list of Indonesian provinces as its choices.
 
+.. versionchanged:: 1.3
+    The province "Nanggroe Aceh Darussalam (NAD)" has been removed
+    from the province list in favor of the new official designation
+    "Aceh (ACE)".
+
 .. class:: id.forms.IDPhoneNumberField
 
     A form field that validates input as an Indonesian telephone number.

docs/releases/1.3.txt

@@ -209,6 +209,17 @@ problem.
 .. _Scunthorpe problem: http://en.wikipedia.org/wiki/Scunthorpe_problem
 .. _commit that implemented this change: http://code.djangoproject.com/changeset/13996
 
+Localflavor changes
+~~~~~~~~~~~~~~~~~~~
+
+Django 1.3 introduces the following backwards-incompatible changes to
+local flavors:
+
+    * Indonesia (id) -- The province "Nanggroe Aceh Darussalam (NAD)"
+      has been removed from the province list in favor of the new
+      official designation "Aceh (ACE)".
+
+
 .. _deprecated-features-1.3:
 
 Features deprecated in 1.3