Allow to disable rule caching by setting "DIAZO_ALWAYS_CACHE_RULES" t…

docs/index.rst

@@ -741,7 +741,7 @@ Theme debugging
 ~~~~~~~~~~~~~~~
 
 When Zope is in development mode (e.g. running in the foreground in a console with ``bin/instance fg``),
-the theme will be re-compiled on each request (unless the environment variable ``DIAZO_ALWAYS_CACHE_RULES`` is set).
+the theme will be re-compiled on each request (unless the environment variable ``DIAZO_ALWAYS_CACHE_RULES`` is set to a truthy value).
 
 To set the environment variable ``DIAZO_ALWAYS_CACHE_RULES``,
 you can use buildout::
@@ -755,6 +755,8 @@ you can use buildout::
 In non-development mode or when the environment variable ``DIAZO_ALWAYS_CACHE_RULES`` is set,
 the theme is compiled once when first accessed, and then only re-compiled the control panel values are changed.
 
+You can also disable caching without removing the environment variable by setting it to a value which evaluates to ``False``, like ``DIAZO_ALWAYS_CACHE_RULES false``
+
 Also, in development mode (even when the environment variable ``DIAZO_ALWAYS_CACHE_RULES`` is set),
 it is possible to temporarily disable the theme by appending a query string parameter ``diazo.off=1``.
 

news/245.bugfix

@@ -0,0 +1,2 @@
+Allow to disable rule caching by setting "DIAZO_ALWAYS_CACHE_RULES" to a value which evaluates to False.
+[thet]

src/plone/app/theming/policy.py

@@ -76,8 +76,7 @@ def isThemeEnabled(self, settings=None):
             return False
 
         # Check for diazo.off request parameter
-        true_vals = ("1", "y", "yes", "t", "true")
-        if debug_mode and self.request.get("diazo.off", "").lower() in true_vals:
+        if debug_mode and utils.is_truthy(self.request.get("diazo.off", False)):
             return False
 
         if not settings:

src/plone/app/theming/tests/test_utils.py

@@ -482,6 +482,32 @@ def _open_zipfile(self, filename):
         path = os.path.join(os.path.dirname(__file__), "zipfiles", filename)
         return open(path, "rb")
 
+    def test_is_truthy(self):
+        """Test the `is_truthy` utility function with different inputs."""
+        from plone.app.theming.utils import is_truthy
+
+        self.assertTrue(is_truthy(True))
+        self.assertTrue(is_truthy(1))
+        self.assertTrue(is_truthy("1"))
+        self.assertTrue(is_truthy("TRUE"))
+        self.assertTrue(is_truthy("tRUE"))
+        self.assertTrue(is_truthy("true"))
+        self.assertTrue(is_truthy("y"))
+        self.assertTrue(is_truthy("Y"))
+        self.assertTrue(is_truthy("yEs"))
+        self.assertTrue(is_truthy("yes"))
+
+        self.assertFalse(is_truthy(None))
+        self.assertFalse(is_truthy(False))
+        self.assertFalse(is_truthy(0))
+        self.assertFalse(is_truthy("0"))
+        self.assertFalse(is_truthy("FALSE"))
+        self.assertFalse(is_truthy("fALSE"))
+        self.assertFalse(is_truthy("false"))
+        self.assertFalse(is_truthy("n"))
+        self.assertFalse(is_truthy("NO"))
+        self.assertFalse(is_truthy("no"))
+
     def test_extractThemeInfo_default_rules(self):
         with self._open_zipfile("default_rules.zip") as fp:
             zf = zipfile.ZipFile(fp)

src/plone/app/theming/transform.py

@@ -1,12 +1,8 @@
 from App.config import getConfiguration
 from lxml import etree
 from os import environ
+from plone.app.theming import utils
 from plone.app.theming.interfaces import IThemingLayer
-from plone.app.theming.utils import compileThemeTransform
-from plone.app.theming.utils import findContext
-from plone.app.theming.utils import getParser
-from plone.app.theming.utils import prepareThemeParameters
-from plone.app.theming.utils import theming_policy
 from plone.app.theming.zmi import patch_zmi
 from plone.transformchain.interfaces import ITransform
 from repoze.xmliter.utils import getHTMLSerializer
@@ -55,13 +51,13 @@ def develop_theme(self):
             return False
         if self.debug_theme():
             return True
-        if environ.get("DIAZO_ALWAYS_CACHE_RULES"):
+        if utils.is_truthy(environ.get("DIAZO_ALWAYS_CACHE_RULES", False)):
             return False
         return True
 
     def setupTransform(self, runtrace=False):
         debug_mode = self.develop_theme()
-        policy = theming_policy(self.request)
+        policy = utils.theming_policy(self.request)
 
         # Obtain settings. Do nothing if not found
         settings = policy.getSettings()
@@ -89,7 +85,7 @@ def setupTransform(self, runtrace=False):
             readNetwork = settings.readNetwork
             parameterExpressions = settings.parameterExpressions
 
-            transform = compileThemeTransform(
+            transform = utils.compileThemeTransform(
                 rules,
                 absolutePrefix,
                 readNetwork,
@@ -105,7 +101,7 @@ def setupTransform(self, runtrace=False):
         return transform
 
     def getSettings(self):
-        return theming_policy(self.request).getSettings()
+        return utils.theming_policy(self.request).getSettings()
 
     def parseTree(self, result):
         contentType = self.request.response.getHeader("Content-Type")
@@ -146,7 +142,7 @@ def transformUnicode(self, result, encoding):
     def transformIterable(self, result, encoding):
         """Apply the transform if required"""
         # Obtain settings. Do nothing if not found
-        policy = theming_policy(self.request)
+        policy = utils.theming_policy(self.request)
         if not policy.isThemeEnabled():
             return None
         settings = policy.getSettings()
@@ -177,8 +173,11 @@ def transformIterable(self, result, encoding):
                 cache = policy.getCache()
 
             parameterExpressions = settings.parameterExpressions or {}
-            params = prepareThemeParameters(
-                findContext(self.request), self.request, parameterExpressions, cache
+            params = utils.prepareThemeParameters(
+                utils.findContext(self.request),
+                self.request,
+                parameterExpressions,
+                cache,
             )
 
             transformed = transform(result.tree, **params)
@@ -198,14 +197,15 @@ def transformIterable(self, result, encoding):
             # Add debug information to end of body
             body = result.tree.xpath("/html/body")[0]
             debug_url = (
-                findContext(self.request).portal_url() + "/++resource++diazo-debug"
+                utils.findContext(self.request).portal_url()
+                + "/++resource++diazo-debug"
             )
             body.insert(
                 -1,
                 generate_debug_html(
                     debug_url,
                     rules=settings.rules,
-                    rules_parser=getParser("rules", settings.readNetwork),
+                    rules_parser=utils.getParser("rules", settings.readNetwork),
                     error_log=error_log,
                 ),
             )

src/plone/app/theming/utils.py

@@ -43,6 +43,11 @@
 LOGGER = logging.getLogger("plone.app.theming")
 
 
+def is_truthy(value):
+    """Return `true`, if value is truthy."""
+    return value and str(value).lower() in ("1", "y", "yes", "t", "true")
+
+
 @implementer(INoRequest)
 class NoRequest:
     """Fallback to enable querying for the policy adapter