Simplified caching of templatetags modules.

from django.conf import settings

from django.template.context import (BaseContext, Context, RequestContext,  # NOQA: imported for backwards compatibility

    ContextPopException)

from django.utils import lru_cache

from django.utils.deprecation import RemovedInDjango20Warning

from django.utils.itercompat import is_iterable

from django.utils.text import (smart_split, unescape_string_literal,

                                     "a variable named 'register'" %

                                     taglib_module)

templatetags_modules = []

@lru_cache.lru_cache()

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 process. Mutate the local list first, and

        # then assign it to the global name to ensure there are no cases where

        # two threads try to populate it simultaneously.

    templatetags_modules_candidates = ['django.templatetags']

        templatetags_modules_candidates += ['%s.templatetags' % app_config.name

    templatetags_modules_candidates += [

        '%s.templatetags' % app_config.name

        for app_config in apps.get_app_configs()]

    templatetags_modules = []

    for templatetag_module in templatetags_modules_candidates:

        try:

            import_module(templatetag_module)

                _templatetags_modules.append(templatetag_module)

        except ImportError:

            continue

        templatetags_modules = _templatetags_modules

        else:

            templatetags_modules.append(templatetag_module)

    return templatetags_modules

        from django.core.management import get_commands

        get_commands.cache_clear()

        # Rebuild templatetags module cache.

        from django.template import base as mod

        mod.templatetags_modules = []

        from django.template.base import get_templatetags_modules

        get_templatetags_modules.cache_clear()

        # Rebuild get_app_template_dirs cache.

        from django.template.utils import get_app_template_dirs

        get_app_template_dirs.cache_clear()

    def setUp(self):

        self.egg_dir = '%s/eggs' % os.path.dirname(upath(__file__))

        self.old_tag_modules = template_base.templatetags_modules

        template_base.templatetags_modules = []

    def tearDown(self):

        template_base.templatetags_modules = self.old_tag_modules

    def test_load_error(self):

        ttext = "{% load broken_tag %}"