Fixed #6587 -- Removed nasty __path__ hacking in templatetag loading. Thanks to Øyvind Satvik and Andrew Badr for their work on this patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12295 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admindocs/views.py

@@ -309,12 +309,17 @@ def missing_docutils_page(request):
 
 def load_all_installed_template_libraries():
     # Load/register all template tag libraries from installed apps.
-    for e in templatetags.__path__:
-        libraries = [os.path.splitext(p)[0] for p in os.listdir(e) if p.endswith('.py') and p[0].isalpha()]
+    for module_name in template.get_templatetags_modules():
+        mod = import_module(module_name)
+        libraries = [
+            os.path.splitext(p)[0]
+            for p in os.listdir(os.path.dirname(mod.__file__))
+            if p.endswith('.py') and p[0].isalpha()
+        ]
         for library_name in libraries:
             try:
-                lib = template.get_library("django.templatetags.%s" % library_name.split('.')[-1])
-            except template.InvalidTemplateLibrary:
+                lib = template.get_library(library_name)
+            except template.InvalidTemplateLibrary, e:
                 pass
 
 def get_return_data_type(func_name):

django/template/__init__.py

@@ -966,22 +966,70 @@ class Library(object):
             return func
         return dec
 
-def get_library(module_name):
-    lib = libraries.get(module_name, None)
+def import_library(taglib_module):
+    """Load a template tag library module.
+
+    Verifies that the library contains a 'register' attribute, and
+    returns that attribute as the representation of the library
+    """
+    try:
+        mod = import_module(taglib_module)
+    except ImportError:
+        return None
+    try:
+        return mod.register
+    except AttributeError:
+        raise InvalidTemplateLibrary("Template library %s does not have a variable named 'register'" % taglib_module)
+
+templatetags_modules = []
+
+def get_templatetags_modules():
+    """Return the list of all available template tag modules.
+
+    Caches the result for faster access.
+    """
+    global templatetags_modules
+    if not templatetags_modules:
+        _templatetags_modules = []
+        # Populate list once per thread.
+        for app_module in ['django'] + list(settings.INSTALLED_APPS):
+            try:
+                templatetag_module = '%s.templatetags' % app_module
+                import_module(templatetag_module)
+                _templatetags_modules.append(templatetag_module)
+            except ImportError:
+                continue
+        templatetags_modules = _templatetags_modules
+    return templatetags_modules
+
+def get_library(library_name):
+    """
+    Load the template library module with the given name.
+
+    If library is not already loaded loop over all templatetags modules to locate it.
+
+    {% load somelib %} and {% load someotherlib %} loops twice.
+
+    Subsequent loads eg. {% load somelib %} in the same process will grab the cached
+    module from libraries.
+    """
+    lib = libraries.get(library_name, None)
     if not lib:
-        try:
-            mod = import_module(module_name)
-        except ImportError, e:
-            raise InvalidTemplateLibrary("Could not load template library from %s, %s" % (module_name, e))
-        try:
-            lib = mod.register
-            libraries[module_name] = lib
-        except AttributeError:
-            raise InvalidTemplateLibrary("Template library %s does not have a variable named 'register'" % module_name)
+        templatetags_modules = get_templatetags_modules()
+        tried_modules = []
+        for module in templatetags_modules:
+            taglib_module = '%s.%s' % (module, library_name)
+            tried_modules.append(taglib_module)
+            lib = import_library(taglib_module)
+            if lib:
+                libraries[library_name] = lib
+                break
+        if not lib:
+            raise InvalidTemplateLibrary("Template library %s not found, tried %s" % (library_name, ','.join(tried_modules)))
     return lib
 
-def add_to_builtins(module_name):
-    builtins.append(get_library(module_name))
+def add_to_builtins(module):
+    builtins.append(import_library(module))
 
 add_to_builtins('django.template.defaulttags')
 add_to_builtins('django.template.defaultfilters')

django/template/defaulttags.py

@@ -920,7 +920,7 @@ def load(parser, token):
     for taglib in bits[1:]:
         # add the library to the parser
         try:
-            lib = get_library("django.templatetags.%s" % taglib)
+            lib = get_library(taglib)
             parser.add_library(lib)
         except InvalidTemplateLibrary, e:
             raise TemplateSyntaxError("'%s' is not a valid tag library: %s" %

django/templatetags/__init__.py

@@ -1,8 +0,0 @@
-from django.conf import settings
-from django.utils import importlib
-
-for a in settings.INSTALLED_APPS:
-    try:
-        __path__.extend(importlib.import_module('.templatetags', a).__path__)
-    except ImportError:
-        pass

tests/regressiontests/templates/tests.py

@@ -59,7 +59,7 @@ def do_echo(parser, token):
 
 register.tag("echo", do_echo)
 
-template.libraries['django.templatetags.testtags'] = register
+template.libraries['testtags'] = register
 
 #####################################
 # Helper objects for template tests #