deprecated init_jinja_globals

CHANGES

@@ -40,6 +40,9 @@ Release date to be announced, codename to be selected
 - Added `teardown_request` decorator, for functions that should run at the end
   of a request regardless of whether an exception occurred.
 - Implemented :func:`flask.has_request_context`
+- Deprecated `init_jinja_globals`.  Override the
+  :meth:`~flask.Flask.create_jinja_environment` method instead to
+  achieve the same functionality.
 
 Version 0.6.1
 -------------

flask/app.py

@@ -24,7 +24,7 @@ from werkzeug.exceptions import HTTPException, InternalServerError, \
      MethodNotAllowed
 
 from .helpers import _PackageBoundObject, url_for, get_flashed_messages, \
-    _tojson_filter, _endpoint_from_view_func
+    locked_cached_property, _tojson_filter, _endpoint_from_view_func
 from .wrappers import Request, Response
 from .config import ConfigAttribute, Config
 from .ctx import _RequestContext
@@ -317,11 +317,6 @@ class Flask(_PackageBoundObject):
                           endpoint='static',
                           view_func=self.send_static_file)
 
-        #: The Jinja2 environment.  It is created from the
-        #: :attr:`jinja_options`.
-        self.jinja_env = self.create_jinja_environment()
-        self.init_jinja_globals()
-
     @property
     def propagate_exceptions(self):
         """Returns the value of the `PROPAGATE_EXCEPTIONS` configuration
@@ -356,16 +351,43 @@ class Flask(_PackageBoundObject):
             self._logger = rv = create_logger(self)
             return rv
 
+    @locked_cached_property
+    def jinja_env(self):
+        """The Jinja2 environment used to load templates."""
+        rv = self.create_jinja_environment()
+
+        # Hack to support the init_jinja_globals method which is supported
+        # until 1.0 but has an API deficiency.
+        if getattr(self.init_jinja_globals, 'im_func', None) is not \
+           Flask.init_jinja_globals.im_func:
+            from warnings import warn
+            warn(DeprecationWarning('This flask class uses a customized '
+                'init_jinja_globals() method which is deprecated. '
+                'Move the code from that method into the '
+                'create_jinja_environment() method instead.'))
+            self.__dict__['jinja_env'] = rv
+            self.init_jinja_globals()
+
+        return rv
+
     def create_jinja_environment(self):
         """Creates the Jinja2 environment based on :attr:`jinja_options`
-        and :meth:`select_jinja_autoescape`.
+        and :meth:`select_jinja_autoescape`.  Since 0.7 this also adds
+        the Jinja2 globals and filters after initialization.  Override
+        this function to customize the behavior.
 
         .. versionadded:: 0.5
         """
         options = dict(self.jinja_options)
         if 'autoescape' not in options:
             options['autoescape'] = self.select_jinja_autoescape
-        return Environment(loader=self.create_jinja_loader(), **options)
+        rv = Environment(loader=self.create_jinja_loader(), **options)
+        rv.globals.update(
+            url_for=url_for,
+            get_flashed_messages=get_flashed_messages
+        )
+        rv.filters['tojson'] = _tojson_filter
+        return rv
 
     def create_jinja_loader(self):
         """Creates the loader for the Jinja2 environment.  Can be used to
@@ -376,17 +398,13 @@ class Flask(_PackageBoundObject):
         return _DispatchingJinjaLoader(self)
 
     def init_jinja_globals(self):
-        """Called directly after the environment was created to inject
-        some defaults (like `url_for`, `get_flashed_messages` and the
-        `tojson` filter.
+        """Deprecated.  Used to initialize the Jinja2 globals.
 
         .. versionadded:: 0.5
+        .. versionchanged:: 0.7
+           This method is deprecated with 0.7.  Override
+           :meth:`create_jinja_environment` instead.
         """
-        self.jinja_env.globals.update(
-            url_for=url_for,
-            get_flashed_messages=get_flashed_messages
-        )
-        self.jinja_env.filters['tojson'] = _tojson_filter
 
     def select_jinja_autoescape(self, filename):
         """Returns `True` if autoescaping should be active for the given

flask/helpers.py

@@ -15,6 +15,7 @@ import posixpath
 import mimetypes
 from time import time
 from zlib import adler32
+from threading import RLock
 
 # try to load the best simplejson implementation available.  If JSON
 # is not installed, we add a failing class.
@@ -58,6 +59,10 @@ else:
     _tojson_filter = json.dumps
 
 
+# sentinel
+_missing = object()
+
+
 # what separators does this operating system provide that are not a slash?
 # this is used by the send_from_directory function to ensure that nobody is
 # able to access files from outside the filesystem.
@@ -435,6 +440,32 @@ def _get_package_path(name):
         return os.getcwd()
 
 
+class locked_cached_property(object):
+    """A decorator that converts a function into a lazy property.  The
+    function wrapped is called the first time to retrieve the result
+    and then that calculated result is used the next time you access
+    the value.  Works like the one in Werkzeug but has a lock for
+    thread safety.
+    """
+
+    def __init__(self, func, name=None, doc=None):
+        self.__name__ = name or func.__name__
+        self.__module__ = func.__module__
+        self.__doc__ = doc or func.__doc__
+        self.func = func
+        self.lock = RLock()
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+        with self.lock:
+            value = obj.__dict__.get(self.__name__, _missing)
+            if value is _missing:
+                value = self.func(obj)
+                obj.__dict__[self.__name__] = value
+            return value
+
+
 class _PackageBoundObject(object):
 
     def __init__(self, import_name):

tests/flask_tests.py

@@ -1564,6 +1564,25 @@ class TestSignals(unittest.TestCase):
             flask.got_request_exception.disconnect(record, app)
 
 
+class DeprecationsTestCase(unittest.TestCase):
+
+    def test_init_jinja_globals(self):
+        class MyFlask(flask.Flask):
+            def init_jinja_globals(self):
+                self.jinja_env.globals['foo'] = '42'
+
+        with catch_warnings() as log:
+            app = MyFlask(__name__)
+            @app.route('/')
+            def foo():
+                return app.jinja_env.globals['foo']
+
+            c = app.test_client()
+            assert c.get('/').data == '42'
+            assert len(log) == 1
+            assert 'init_jinja_globals' in str(log[0]['message'])
+
+
 def suite():
     from minitwit_tests import MiniTwitTestCase
     from flaskr_tests import FlaskrTestCase
@@ -1576,6 +1595,7 @@ def suite():
     suite.addTest(unittest.makeSuite(LoggingTestCase))
     suite.addTest(unittest.makeSuite(ConfigTestCase))
     suite.addTest(unittest.makeSuite(SubdomainTestCase))
+    suite.addTest(unittest.makeSuite(DeprecationsTestCase))
     if flask.json_available:
         suite.addTest(unittest.makeSuite(JSONTestCase))
     if flask.signals_available: