LP #143232: Added option to 'zope.conf' to specify an extensions directory.

o This directory is searched for 'App.Extensions' lookups.  Thanks to Rodrigo
  Senra for the patch.

doc/CHANGES.rst

@@ -100,6 +100,10 @@ Restructuring
 Features Added
 ++++++++++++++
 
+- LP #143232: Added option to 'zope.conf' to specify an additional directory
+  to be searched for 'App.Extensions' lookups.  Thanks to Rodrigo Senra for
+  the patch.
+
 - Integrated the Products.signalstack / z3c.deadlockdebugger packages. You can
   now send a SIGUSR1 signal to a Zope process and get a stack trace of all
   threads printed out on the console. This works even if all threads are stuck.

src/App/Extensions.py

@@ -106,6 +106,11 @@ def getPath(prefix, name, checkProduct=1, suffixes=('',), cfg=None):
         import App.config
         cfg = App.config.getConfiguration()
 
+    if prefix == "Extensions" and getattr(cfg, 'extensions', None) is not None:
+        found = _getPath(cfg.extensions, '', name, suffixes)
+        if found is not None:
+            return found
+
     locations = [cfg.instancehome]
 
     softwarehome = getattr(cfg, 'softwarehome', None)

src/App/tests/test_Extensions.py

@@ -201,6 +201,23 @@ class Test_getPath(_TempdirBase, unittest.TestCase):
                              suffixes=('py',), cfg=cfg)
         self.assertEqual(path, instfqn)
 
+    def test_w_cfg_extensions(self):
+        cfgdir = self._makeTempdir()
+        cfgfqn = self._makeFile(cfgdir, 'extension.py')
+        instdir = self._makeTempdir()
+        instext = self._makeTempExtension(name=None, dir=instdir)
+        instfqn = self._makeFile(instext, 'extension.py')
+        swdir = self._makeTempdir()
+        swext = self._makeTempExtension(name=None, dir=swdir)
+        swfqn = self._makeFile(swext, 'extension.py')
+        cfg = self._makeConfig(extensions=cfgdir,
+                               instancehome=instdir,
+                               softwarehome=swdir,
+                              )
+        path = self._callFUT('Extensions', 'extension', checkProduct=0,
+                             suffixes=('py',), cfg=cfg)
+        self.assertEqual(path, cfgfqn)
+
     def test_not_found_in_instancehome(self):
         import os
         instdir = self._makeTempdir()
@@ -258,6 +275,27 @@ class Test_getPath(_TempdirBase, unittest.TestCase):
                                 suffixes=('py',), cfg=cfg)
         self.assertEqual(path, subpkgfqn)
 
+"""
+Index: lib/python/App/Extensions.py
+===================================================================
+--- lib/python/App/Extensions.py	(revision 28473)
++++ lib/python/App/Extensions.py	(working copy)
+@@ -87,8 +87,14 @@
+                 r = _getPath(product_dir, os.path.join(p, prefix), n, suffixes)
+                 if r is not None: return r
+ 
++        
+     import App.config
+     cfg = App.config.getConfiguration()
++
++    if (prefix=="Extensions") and (cfg.extensions is not None):
++        r=_getPath(cfg.extensions, '', name, suffixes)
++        if r is not None: return r
++        
+     sw=os.path.dirname(os.path.dirname(cfg.softwarehome))
+     for home in (cfg.instancehome, sw):
+         r=_getPath(home, prefix, name, suffixes)
+"""
 
 class Test_getObject(_TempdirBase, unittest.TestCase):
 

src/Products/ExternalMethod/ExternalMethod.py

@@ -47,7 +47,7 @@ manage_addExternalMethodForm=DTMLFile('dtml/methodAdd', globals())
 def manage_addExternalMethod(self, id, title, module, function, REQUEST=None):
     """Add an external method to a folder
 
-    Un addition to the standard object-creation arguments,
+    In addition to the standard object-creation arguments,
     'id' and title, the following arguments are defined:
 
         function -- The name of the python function. This can be a
@@ -56,8 +56,12 @@ def manage_addExternalMethod(self, id, title, module, function, REQUEST=None):
         module -- The name of the file containing the function
           definition.
 
-        The module normally resides in the 'Extensions'
-        directory, however, the file name may have a prefix of
+        The module normally resides in the 'Extensions' directory.
+
+        If the zope.conf directive 'extensions' was overriden, then
+        it will specify where modules should reside.
+
+        However, the file name may have a prefix of
         'product.', indicating that it should be found in a product
         directory.
         
@@ -84,7 +88,8 @@ class ExternalMethod(Item, Persistent, Explicit,
     The function is defined in an external file.  This file is treated
     like a module, but is not a module.  It is not imported directly,
     but is rather read and evaluated.  The file must reside in the
-    'Extensions' subdirectory of the Zope installation, or in an
+    'Extensions' subdirectory of the Zope installation, or in the directory
+     specified by the 'extensions' directive in zope.conf, or in an
     'Extensions' subdirectory of a product directory.
 
     Due to the way ExternalMethods are loaded, it is not *currently*
@@ -131,7 +136,7 @@ class ExternalMethod(Item, Persistent, Explicit,
         """Change the external method
 
         See the description of manage_addExternalMethod for a
-        descriotion of the arguments 'module' and 'function'.
+        description of the arguments 'module' and 'function'.
 
         Note that calling 'manage_edit' causes the "module" to be
         effectively reloaded.  This is useful during debugging to see

src/Products/ExternalMethod/help/ExternalMethod.py

@@ -48,7 +48,8 @@ class ExternalMethod:
     The function is defined in an external file.  This file is treated
     like a module, but is not a module.  It is not imported directly,
     but is rather read and evaluated.  The file must reside in the
-    'Extensions' subdirectory of the Zope installation, or in an
+    'Extensions' subdirectory of the Zope installation, or reside in
+    the path specified by 'extensions' directive in zope.conf, or in an
     'Extensions' subdirectory of a product directory.
 
     Due to the way ExternalMethods are loaded, it is not *currently*

src/Zope2/Startup/zopeschema.xml

@@ -343,6 +343,14 @@
     <metadefault>$instancehome/Products</metadefault>
   </multikey>
 
+
+  <key name="extensions" datatype="existing-directory">
+    <description>
+      This overrides the path to the Extensions directory.
+    </description>
+    <metadefault>$instancehome/Extensions</metadefault>
+  </key>
+  
   <multikey name="path" datatype="string">
     <description>
       This specifies additional paths directories which are inserted into

src/Zope2/utilities/skel/etc/zope.conf.in

@@ -91,6 +91,21 @@ instancehome $INSTANCE
 #    products /home/chrism/projects/myproducts
 
 
+# Directive: extensions
+#
+# Description:
+#     Name of a directory that contains additional "extensions"
+#     (implementations of ExternalMethods or catalog brains).  This
+#     directive The directory identified will be searched before the
+#     'Extensions' directory of the 'instancehome'.
+#
+# Default: unset
+#
+# Example:
+#
+#    extensions /home/chrism/extensions
+
+
 # Directive: environment
 #
 # Description: