Use the Django>=1.7 app registry

- Drops support for anything < 1.7.
- Use `django.apps.apps.get_app_configs()` for template loaders and
  helper discovery.
- Delays environment creation as long as possible, and caches it, should
  fix #50.
- Removes direct access to jingo.env, use jingo.get_env() instead.
- Removes env dependency from Registry().
- Moves Template() higher in the module and sets
  Environment().template_class directly.
- Adds `django.contrib.admin.apps.SimpleAdminConfig` to test settings
  to ensure support for AppConfig classes, fixes #68.

docs/index.rst

@@ -51,9 +51,9 @@ class with a literal string, e.g.::
 
 then you'll need to change that code slightly, to::
 
-    from jingo import env
+    from jingo import get_env
 
-    t = env.from_string('template_string')
+    t = get_env().from_string('template_string')
 
 and then the template will be rendered with all the same features that Jingo
 provides when rendering template files.

fake_settings.py

@@ -4,6 +4,7 @@ path = lambda *a: os.path.join(ROOT, *a)
 
 ROOT = os.path.dirname(os.path.abspath(__file__))
 INSTALLED_APPS = (
+    'django.contrib.admin.apps.SimpleAdminConfig',
     'jingo.tests.jinja_app',
     'jingo.tests.django_app',
 )

jingo/__init__.py

@@ -7,6 +7,7 @@ import imp
 import logging
 import re
 
+from django.apps import apps
 from django.conf import settings
 from django.template.base import Origin, TemplateDoesNotExist
 from django.template.loader import BaseLoader
@@ -41,141 +42,6 @@ log = logging.getLogger('jingo')
 _helpers_loaded = False
 
 
-class Environment(jinja2.Environment):
-
-    def get_template(self, name, parent=None, globals=None):
-        """Make sure our helpers get loaded before any templates."""
-        load_helpers()
-        return super(Environment, self).get_template(name, parent, globals)
-
-    def from_string(self, source, globals=None, template_class=None):
-        load_helpers()
-        return super(Environment, self).from_string(source, globals,
-                                                    template_class)
-
-
-def get_env():
-    """Configure and return a jinja2 Environment."""
-    # Mimic Django's setup by loading templates from directories in
-    # TEMPLATE_DIRS and packages in INSTALLED_APPS.
-    x = ((jinja2.FileSystemLoader, settings.TEMPLATE_DIRS),
-         (jinja2.PackageLoader, settings.INSTALLED_APPS))
-    loaders = [loader(p) for loader, places in x for p in places]
-
-    opts = {'trim_blocks': True,
-            'extensions': ['jinja2.ext.i18n'],
-            'autoescape': True,
-            'auto_reload': settings.DEBUG,
-            'loader': jinja2.ChoiceLoader(loaders),
-            }
-
-    if hasattr(settings, 'JINJA_CONFIG'):
-        if hasattr(settings.JINJA_CONFIG, '__call__'):
-            config = settings.JINJA_CONFIG()
-        else:
-            config = settings.JINJA_CONFIG
-        opts.update(config)
-
-    e = Environment(**opts)
-    # Install null translations since gettext isn't always loaded up during
-    # testing.
-    if ('jinja2.ext.i18n' in e.extensions or
-            'jinja2.ext.InternationalizationExtension' in e.extensions):
-        e.install_null_translations()
-    return e
-
-
-def render_to_string(request, template, context=None):
-    """
-    Render a template into a string.
-    """
-    def get_context():
-        c = {} if context is None else context.copy()
-        for processor in get_standard_processors():
-            c.update(processor(request))
-        return c
-
-    # If it's not a Template, it must be a path to be loaded.
-    if not isinstance(template, jinja2.environment.Template):
-        template = env.get_template(template)
-
-    return template.render(get_context())
-
-
-def load_helpers():
-    """Try to import ``helpers.py`` from each app in INSTALLED_APPS."""
-    # We want to wait as long as possible to load helpers so there aren't any
-    # weird circular imports with jingo.
-    global _helpers_loaded
-    if _helpers_loaded:
-        return
-    _helpers_loaded = True
-
-    from jingo import helpers  # noqa
-
-    for app in settings.INSTALLED_APPS:
-        try:
-            app_path = import_module(app).__path__
-        except AttributeError:
-            continue
-
-        try:
-            imp.find_module('helpers', app_path)
-        except ImportError:
-            continue
-
-        import_module('%s.helpers' % app)
-
-
-class Register(object):
-    """Decorators to add filters and functions to the template Environment."""
-
-    def __init__(self, env):
-        self.env = env
-
-    def filter(self, f=None, override=True):
-        """Adds the decorated function to Jinja's filter library."""
-        def decorator(f):
-            @functools.wraps(f)
-            def wrapper(*args, **kw):
-                return f(*args, **kw)
-            return self.filter(wrapper, override)
-
-        if not f:
-            return decorator
-        if override or f.__name__ not in self.env.filters:
-            self.env.filters[f.__name__] = f
-        return f
-
-    def function(self, f=None, override=True):
-        """Adds the decorated function to Jinja's global namespace."""
-        def decorator(f):
-            @functools.wraps(f)
-            def wrapper(*args, **kw):
-                return f(*args, **kw)
-            return self.function(wrapper, override)
-
-        if not f:
-            return decorator
-        if override or f.__name__ not in self.env.globals:
-            self.env.globals[f.__name__] = f
-        return f
-
-    def inclusion_tag(self, template):
-        """Adds a function to Jinja, but like Django's @inclusion_tag."""
-        def decorator(f):
-            @functools.wraps(f)
-            def wrapper(*args, **kw):
-                context = f(*args, **kw)
-                t = env.get_template(template).render(context)
-                return jinja2.Markup(t)
-            return self.function(wrapper)
-        return decorator
-
-env = get_env()
-register = Register(env)
-
-
 class Template(jinja2.Template):
 
     def render(self, context={}):
@@ -206,9 +72,141 @@ class Template(jinja2.Template):
         return super(Template, self).render(context_dict)
 
 
+class Environment(jinja2.Environment):
+    template_class = Template
+
+    def get_template(self, name, parent=None, globals=None):
+        """Make sure our helpers get loaded before any templates."""
+        load_helpers()
+        return super(Environment, self).get_template(name, parent, globals)
+
+    def from_string(self, source, globals=None, template_class=None):
+        load_helpers()
+        return super(Environment, self).from_string(source, globals,
+                                                    template_class)
+
+
+_env = None
+
+
+def get_env():
+    """Configure and return a jinja2 Environment."""
+    global _env
+    if _env:
+        return _env
+    # Mimic Django's setup by loading templates from directories in
+    # TEMPLATE_DIRS and packages in INSTALLED_APPS.
+    loaders = [jinja2.FileSystemLoader(d) for d in settings.TEMPLATE_DIRS]
+    loaders += [jinja2.PackageLoader(c.name) for c in apps.get_app_configs()]
+
+    opts = {
+        'trim_blocks': True,
+        'extensions': ['jinja2.ext.i18n'],
+        'autoescape': True,
+        'auto_reload': settings.DEBUG,
+        'loader': jinja2.ChoiceLoader(loaders),
+    }
+
+    if hasattr(settings, 'JINJA_CONFIG'):
+        if hasattr(settings.JINJA_CONFIG, '__call__'):
+            config = settings.JINJA_CONFIG()
+        else:
+            config = settings.JINJA_CONFIG
+        opts.update(config)
+
+    e = Environment(**opts)
+    # Install null translations since gettext isn't always loaded up during
+    # testing.
+    if ('jinja2.ext.i18n' in e.extensions or
+            'jinja2.ext.InternationalizationExtension' in e.extensions):
+        e.install_null_translations()
+    _env = e
+    return e
+
+
+def render_to_string(request, template, context=None):
+    """
+    Render a template into a string.
+    """
+    def get_context():
+        c = {} if context is None else context.copy()
+        for processor in get_standard_processors():
+            c.update(processor(request))
+        return c
+
+    # If it's not a Template, it must be a path to be loaded.
+    if not isinstance(template, jinja2.environment.Template):
+        template = get_env().get_template(template)
+
+    return template.render(get_context())
+
+
+def load_helpers():
+    """Try to import ``helpers.py`` from each app in INSTALLED_APPS."""
+    # We want to wait as long as possible to load helpers so there aren't any
+    # weird circular imports with jingo.
+    global _helpers_loaded
+    if _helpers_loaded:
+        return
+    _helpers_loaded = True
+
+    from jingo import helpers  # noqa
+
+    for config in apps.get_app_configs():
+        try:
+            imp.find_module('helpers', config.name)
+        except ImportError:
+            continue
+
+        import_module('%s.helpers' % config.name)
+
+
+class Register(object):
+    """Decorators to add filters and functions to the template Environment."""
+    def filter(self, f=None, override=True):
+        """Adds the decorated function to Jinja's filter library."""
+        def decorator(f):
+            @functools.wraps(f)
+            def wrapper(*args, **kw):
+                return f(*args, **kw)
+            return self.filter(wrapper, override)
+
+        if not f:
+            return decorator
+        if override or f.__name__ not in get_env().filters:
+            get_env().filters[f.__name__] = f
+        return f
+
+    def function(self, f=None, override=True):
+        """Adds the decorated function to Jinja's global namespace."""
+        def decorator(f):
+            @functools.wraps(f)
+            def wrapper(*args, **kw):
+                return f(*args, **kw)
+            return self.function(wrapper, override)
+
+        if not f:
+            return decorator
+        if override or f.__name__ not in get_env().globals:
+            get_env().globals[f.__name__] = f
+        return f
+
+    def inclusion_tag(self, template):
+        """Adds a function to Jinja, but like Django's @inclusion_tag."""
+        def decorator(f):
+            @functools.wraps(f)
+            def wrapper(*args, **kw):
+                context = f(*args, **kw)
+                t = get_env().get_template(template).render(context)
+                return jinja2.Markup(t)
+            return self.function(wrapper)
+        return decorator
+
+register = Register()
+
+
 class Loader(BaseLoader):
     is_usable = True
-    env.template_class = Template
 
     def __init__(self):
         if has_engine:
@@ -238,7 +236,7 @@ class Loader(BaseLoader):
             raise TemplateDoesNotExist(template_name)
 
         try:
-            template = env.get_template(template_name)
+            template = get_env().get_template(template_name)
             return template, template.filename
         except jinja2.TemplateNotFound:
             raise TemplateDoesNotExist(template_name)
@@ -248,7 +246,7 @@ class Loader(BaseLoader):
             raise TemplateDoesNotExist(template_name)
 
         try:
-            template = env.get_template(template_name)
+            template = get_env().get_template(template_name)
         except jinja2.TemplateNotFound:
             raise TemplateDoesNotExist(template_name)
 

jingo/tests/test_basics.py

@@ -12,10 +12,12 @@ except ImportError:
 import jingo
 
 
-@patch('jingo.env')
+@patch('jingo.get_env')
-def test_render(mock_env):
+def test_render(mock_get_env):
     mock_template = Mock()
+    mock_env = Mock()
     mock_env.get_template.return_value = mock_template
+    mock_get_env.return_value = mock_env
 
     response = render(Mock(), sentinel.template, status=32)
     mock_env.get_template.assert_called_with(sentinel.template)
@@ -24,19 +26,22 @@ def test_render(mock_env):
     eq_(response.status_code, 32)
 
 
-@patch('jingo.env')
+@patch('jingo.get_env')
-def test_render_to_string(mock_env):
+def test_render_to_string(mock_get_env):
     template = jinja2.environment.Template('The answer is {{ answer }}')
     rendered = jingo.render_to_string(Mock(), template, {'answer': 42})
 
     eq_(rendered, 'The answer is 42')
 
 
-@patch('jingo.env.get_template')
+def test_inclusion_tag():
-def test_inclusion_tag(get_template):
     @jingo.register.inclusion_tag('xx.html')
     def tag(x):
         return {'z': x}
-    get_template.return_value = jinja2.environment.Template('<{{ z }}>')
+
-    t = jingo.env.from_string('{{ tag(1) }}')
+    env = jingo.get_env()
+    with patch.object(env, 'get_template') as mock_get_template:
+        temp = jinja2.environment.Template('<{{ z }}>')
+        mock_get_template.return_value = temp
+        t = env.from_string('{{ tag(1) }}')
         eq_('<1>', t.render())

jingo/tests/utils.py

@@ -1,7 +1,7 @@
 from django.test.html import HTMLParseError, parse_html
 from nose.tools import eq_
 
-from jingo import env
+from jingo import get_env
 
 
 def htmleq_(html1, html2, msg=None):
@@ -31,5 +31,5 @@ def assert_and_parse_html(html, user_msg, msg):
 
 
 def render(s, context={}):
-    t = env.from_string(s)
+    t = get_env().from_string(s)
     return t.render(context)