Fixed #16787 -- Restored the ability to {% load %} template tags libraries...

            return func

        return dec

def is_library_missing(name):

    """Check if library that failed to load cannot be found under any

    templatetags directory or does exist but fails to import.

    Non-existing condition is checked recursively for each subpackage in cases

    like <appdir>/templatetags/subpackage/package/module.py.

    """

    # Don't bother to check if '.' is in name since any name will be prefixed

    # with some template root.

    path, module = name.rsplit('.', 1)

    try:

        package = import_module(path)

        return not module_has_submodule(package, module)

    except ImportError:

        return is_library_missing(path)

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

    """

    app_path, taglib = taglib_module.rsplit('.', 1)

    app_module = import_module(app_path)

    try:

        mod = import_module(taglib_module)

    except ImportError, e:

        # that's not an error that should be raised. If the submodule exists

        # and raised an ImportError on the attempt to load it, that we want

        # to raise.

        if not module_has_submodule(app_module, taglib):

        if is_library_missing(taglib_module):

            return None

        else:

            raise InvalidTemplateLibrary("ImportError raised loading %s: %s" %

Loads a custom template tag set.

For example, the following template would load all the tags and filters

registered in ``somelibrary`` and ``otherlibrary``::

registered in ``somelibrary`` and ``otherlibrary`` located in package

``package``::

    {% load somelibrary otherlibrary %}

    {% load somelibrary package.otherlibrary %}

.. versionchanged:: 1.3

from django import template

register = template.Library()

@register.simple_tag

def echo2(arg):

    return arg

import nonexistent.module