add TEMPLATES_AUTO_RELOAD option to config

CHANGES

@@ -15,6 +15,10 @@ Version 1.0
   Non permanent sessions are not affected by this and will always
   expire if the browser window closes.
 
+- Added ``TEMPLATES_AUTO_RELOAD`` config key. If disabled the 
+  templates will be reloaded only if the application is running in 
+  debug mode. For higher performance it’s possible to disable that.
+
 Version 0.10.2
 --------------
 

docs/config.rst

@@ -174,6 +174,12 @@ The following configuration values are used internally by Flask:
                                   if they are not requested by an
                                   XMLHttpRequest object (controlled by
                                   the ``X-Requested-With`` header)
+``TEMPLATES_AUTO_RELOAD``         Flask checks if template was modified each
+                                  time it is requested and reloads it if
+                                  necessary. But disk I/O is costly and it may
+                                  be viable to disable this feature by setting
+                                  this key to ``False``. This option does not
+                                  affect debug mode.
 ================================= =========================================
 
 .. admonition:: More on ``SERVER_NAME``
@@ -222,6 +228,9 @@ The following configuration values are used internally by Flask:
 .. versionadded:: 1.0
    ``SESSION_REFRESH_EACH_REQUEST``
 
+.. versionadded:: 1.0
+   ``TEMPLATES_AUTO_RELOAD``
+
 Configuring from Files
 ----------------------
 

flask/app.py

@@ -294,6 +294,7 @@ class Flask(_PackageBoundObject):
         'JSON_AS_ASCII':                        True,
         'JSON_SORT_KEYS':                       True,
         'JSONIFY_PRETTYPRINT_REGULAR':          True,
+        'TEMPLATES_AUTO_RELOAD':                True,
     })
 
     #: The rule object to use for URL rules created.  This is used by
@@ -644,10 +645,16 @@ class Flask(_PackageBoundObject):
         this function to customize the behavior.
 
         .. versionadded:: 0.5
+        .. versionchanged:: 1.0
+           ``Environment.auto_reload`` set in accordance with
+           ``TEMPLATES_AUTO_RELOAD`` configuration option.
         """
         options = dict(self.jinja_options)
         if 'autoescape' not in options:
             options['autoescape'] = self.select_jinja_autoescape
+        if 'auto_reload' not in options:
+            options['auto_reload'] = self.debug \
+                or self.config['TEMPLATES_AUTO_RELOAD']
         rv = Environment(self, **options)
         rv.globals.update(
             url_for=url_for,

flask/testsuite/templating.py

@@ -295,6 +295,14 @@ class TemplatingTestCase(FlaskTestCase):
         rv = app.test_client().get('/')
         self.assert_equal(rv.data, b'<h1>Jameson</h1>')
 
+    def test_templates_auto_reload(self):
+        app = flask.Flask(__name__)
+        self.assert_true(app.config['TEMPLATES_AUTO_RELOAD'])
+        self.assert_true(app.jinja_env.auto_reload)
+        app = flask.Flask(__name__)
+        app.config['TEMPLATES_AUTO_RELOAD'] = False
+        self.assert_false(app.jinja_env.auto_reload)
+
 
 def suite():
     suite = unittest.TestSuite()