- When Chameleon page or text templates were added imperatively (via

  ``Configurator.add_view`` or some derivative), they too-eagerly
  attempted to look up the ``reload_templates`` setting via
  ``get_settings``, meaning they were always registered in
  non-auto-reload-mode (the default).  Each now waits until its
  respective ``template`` attribute is accessed to look up the value.

7 files changed, 73 insertions, 2 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index d84e8cb7f..10bc39389 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -4,6 +4,13 @@ Next release
 Bug Fixes
 ---------
 
+- When Chameleon page or text templates were added imperatively (via
+  ``Configurator.add_view`` or some derivative), they too-eagerly
+  attempted to look up the ``reload_templates`` setting via
+  ``get_settings``, meaning they were always registered in
+  non-auto-reload-mode (the default).  Each now waits until its
+  respective ``template`` attribute is accessed to look up the value.
+
 - When a route with the same name as a previously registered route was
   added, the old route was not removed from the mapper's routelist.
   Symptom: the old registered route would be used (and possibly
diff --git a/repoze/bfg/chameleon_text.py b/repoze/bfg/chameleon_text.py
index 50491a3d0..9cb1c989a 100644
--- a/repoze/bfg/chameleon_text.py
+++ b/repoze/bfg/chameleon_text.py
@@ -20,6 +20,7 @@ except ImportError: # pragma: no cover
 from repoze.bfg.interfaces import IResponseFactory
 from repoze.bfg.interfaces import ITemplateRenderer
 
+from repoze.bfg.decorator import reify
 from repoze.bfg.renderers import template_renderer_factory
 from repoze.bfg.settings import get_settings
 from repoze.bfg.threadlocal import get_current_registry
@@ -40,9 +41,13 @@ def renderer_factory(path):
 class TextTemplateRenderer(object):
     implements(ITemplateRenderer)
     def __init__(self, path):
+        self.path = path
+
+    @reify
+    def template(self):
         settings = get_settings()
         auto_reload = settings and settings['reload_templates']
-        self.template = TextTemplateFile(path, auto_reload=auto_reload)
+        return TextTemplateFile(self.path, auto_reload=auto_reload)
 
     def implementation(self):
         return self.template
diff --git a/repoze/bfg/chameleon_zpt.py b/repoze/bfg/chameleon_zpt.py
index bc1a5d22f..9083ff3f7 100644
--- a/repoze/bfg/chameleon_zpt.py
+++ b/repoze/bfg/chameleon_zpt.py
@@ -13,6 +13,7 @@ except ImportError, why: # pragma: no cover
 from repoze.bfg.interfaces import IResponseFactory
 from repoze.bfg.interfaces import ITemplateRenderer
 
+from repoze.bfg.decorator import reify
 from repoze.bfg.renderers import template_renderer_factory
 from repoze.bfg.settings import get_settings
 from repoze.bfg.threadlocal import get_current_registry
@@ -23,9 +24,15 @@ def renderer_factory(path):
 class ZPTTemplateRenderer(object):
     implements(ITemplateRenderer)
     def __init__(self, path):
+        self.path = path
+
+    @reify
+    def template(self):
+        # delay template creation until (hopefully) settings have been
+        # registered
         settings = get_settings()
         auto_reload = settings and settings['reload_templates']
-        self.template = PageTemplateFile(path, auto_reload=auto_reload)
+        return PageTemplateFile(self.path, auto_reload=auto_reload)
 
     def implementation(self):
         return self.template
diff --git a/repoze/bfg/decorator.py b/repoze/bfg/decorator.py
new file mode 100644
index 000000000..69c1e65e2
--- /dev/null
+++ b/repoze/bfg/decorator.py
@@ -0,0 +1,15 @@
+class reify(object):
+
+    """ Put the result of a method which uses this (non-data)
+    descriptor decorator in the instance dict after the first call,
+    effectively replacing the decorator with an instance variable."""
+
+    def __init__(self, wrapped):
+        self.wrapped = wrapped
+
+    def __get__(self, inst, objtype=None):
+        if inst is None:
+            return self
+        val = self.wrapped(inst)
+        setattr(inst, self.wrapped.__name__, val)
+        return val
diff --git a/repoze/bfg/tests/test_chameleon_text.py b/repoze/bfg/tests/test_chameleon_text.py
index 54ffc8b10..007c102e3 100644
--- a/repoze/bfg/tests/test_chameleon_text.py
+++ b/repoze/bfg/tests/test_chameleon_text.py
@@ -47,6 +47,13 @@ class TextTemplateRendererTests(Base, unittest.TestCase):
         from repoze.bfg.interfaces import ITemplateRenderer
         verifyClass(ITemplateRenderer, self._getTargetClass())
 
+    def test_template_reified(self):
+        minimal = self._getTemplatePath('minimal.txt')
+        instance = self._makeOne(minimal)
+        self.failIf('template' in instance.__dict__)
+        template  = instance.template
+        self.assertEqual(template, instance.__dict__['template'])
+
     def test_call(self):
         minimal = self._getTemplatePath('minimal.txt')
         instance = self._makeOne(minimal)
diff --git a/repoze/bfg/tests/test_chameleon_zpt.py b/repoze/bfg/tests/test_chameleon_zpt.py
index 38ef543cf..e4bf8f766 100644
--- a/repoze/bfg/tests/test_chameleon_zpt.py
+++ b/repoze/bfg/tests/test_chameleon_zpt.py
@@ -48,6 +48,13 @@ class ZPTTemplateRendererTests(Base, unittest.TestCase):
         self.assertEqual(result,
                      '<div xmlns="http://www.w3.org/1999/xhtml">\n</div>')
 
+    def test_template_reified(self):
+        minimal = self._getTemplatePath('minimal.pt')
+        instance = self._makeOne(minimal)
+        self.failIf('template' in instance.__dict__)
+        template  = instance.template
+        self.assertEqual(template, instance.__dict__['template'])
+
     def test_call_with_nondict_value(self):
         minimal = self._getTemplatePath('minimal.pt')
         instance = self._makeOne(minimal)
diff --git a/repoze/bfg/tests/test_decorator.py b/repoze/bfg/tests/test_decorator.py
new file mode 100644
index 000000000..b1ac2252d
--- /dev/null
+++ b/repoze/bfg/tests/test_decorator.py
@@ -0,0 +1,23 @@
+import unittest
+
+class TestReify(unittest.TestCase):
+    def _makeOne(self, wrapped):
+        from repoze.bfg.decorator import reify
+        return reify(wrapped)
+
+    def test___get__withinst(self):
+        def wrapped(inst):
+            return 'a'
+        decorator = self._makeOne(wrapped)
+        inst = Dummy()
+        result = decorator.__get__(inst)
+        self.assertEqual(result, 'a')
+        self.assertEqual(inst.__dict__['wrapped'], 'a')
+
+    def test___get__noinst(self):
+        decorator = self._makeOne(None)
+        result = decorator.__get__(None)
+        self.assertEqual(result, decorator)
+
+class Dummy(object):
+    pass