Changed template library system so that it looks for a module-level v…

…ariable named 'register' rather than the first instance of template.Library it finds

git-svn-id: http://code.djangoproject.com/svn/django/trunk@1461 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/template/__init__.py

@@ -890,13 +890,11 @@ def get_library(module_name):
             mod = __import__(module_name, '', '', [''])
         except ImportError, e:
             raise InvalidTemplateLibrary, "Could not load template library from %s, %s" % (module_name, e)
-        for k, v in mod.__dict__.items():
-            if isinstance(v, Library):
-                lib = v
-                libraries[module_name] = lib
-                break
-    if not lib:
-        raise InvalidTemplateLibrary, "Template library %s does not have a Library member" % module_name
+        try:
+            lib = mod.register
+            libraries[module_name] = lib
+        except AttributeError:
+            raise InvalidTemplateLibrary, "Template library %s does not have a variable named 'register'" % module_name
     return lib
 
 def add_to_builtins(module_name):

docs/templates_python.txt

@@ -443,14 +443,13 @@ the given Python module name, not the name of the app.
 Once you've created that Python module, you'll just have to write a bit of
 Python code, depending on whether you're writing filters or tags.
 
-To be a valid tag library, the module contain a module-level variable that is a
-``template.Library`` instance, in which all the tags and filters are
-registered. So, near the top of your module, put the following::
+To be a valid tag library, the module contain a module-level variable named
+``register`` that is a ``template.Library`` instance, in which all the tags and
+filters are registered. So, near the top of your module, put the following::
 
     from django.core import template
-    register = template.Library()
 
-Convention is to call this instance ``register``.
+    register = template.Library()
 
 .. admonition:: Behind the scenes