Flask now runs without the presence of pkg_resources as well.

flask.py

@@ -11,10 +11,10 @@
 """
 import os
 import sys
-import pkg_resources
+
 from threading import local
 from contextlib import contextmanager
-from jinja2 import Environment, PackageLoader
+from jinja2 import Environment, PackageLoader, FileSystemLoader
 from werkzeug import Request as RequestBase, Response as ResponseBase, \
      LocalStack, LocalProxy, create_environ, cached_property, \
      SharedDataMiddleware
@@ -27,6 +27,15 @@ from werkzeug.contrib.securecookie import SecureCookie
 from werkzeug import abort, redirect
 from jinja2 import Markup, escape
 
+# use pkg_resource if that works, otherwise fall back to cwd.  The
+# current working directory is generally not reliable with the notable
+# exception of google appengine.
+try:
+    import pkg_resources
+    pkg_resources.resource_stream
+except (ImportError, AttributeError):
+    pkg_resources = None
+
 
 class Request(RequestBase):
     """The request object used by default in flask.  Remembers the
@@ -202,6 +211,10 @@ class Flask(object):
         #: it was set by the constructor.
         self.package_name = package_name
 
+        #: where is the app root located?
+        self.root_path = os.path.abspath(os.path.dirname(
+            sys.modules[self.package_name].__file__))
+
         #: a dictionary of all view functions registered.  The keys will
         #: be function names which are also used to generate URLs and
         #: the values are the function objects themselves.
@@ -242,8 +255,12 @@ class Flask(object):
         if self.static_path is not None:
             self.url_map.add(Rule(self.static_path + '/<filename>',
                                   build_only=True, endpoint='static'))
+            if pkg_resources is not None:
+                target = (self.package_name, 'static')
+            else:
+                target = os.path.join(self.root_path, 'static')
             self.wsgi_app = SharedDataMiddleware(self.wsgi_app, {
-                self.static_path: (self.package_name, 'static')
+                self.static_path: target
             })
 
         #: the Jinja2 environment.  It is created from the
@@ -262,6 +279,8 @@ class Flask(object):
         `templates` folder.  To add other loaders it's possible to
         override this method.
         """
+        if pkg_resources is None:
+            return FileSystemLoader(os.path.join(self.root_path, 'templates'))
         return PackageLoader(self.package_name)
 
     def update_template_context(self, context):
@@ -323,6 +342,8 @@ class Flask(object):
         :param resource: the name of the resource.  To access resources within
                          subfolders use forward slashes as separator.
         """
+        if pkg_resources is None:
+            return open(os.path.join(self.root_path, resource), 'rb')
         return pkg_resources.resource_stream(self.package_name, resource)
 
     def open_session(self, request):