Merged from trunk 26023:

Implemented a thread-local data proposal

Proposed for Python 2.4 on python-dev:
  http://mail.python.org/pipermail/python-dev/2004-June/045785.html    

This mechanism replaces the previous "thread globals"
mechanism.

hooks.py

@@ -0,0 +1,90 @@
+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""
+
+$Id$
+"""
+
+from zope.component import getService, getAdapter
+from zope.component.interfaces import IServiceService
+from zope.app.site.interfaces import ISite
+from zope.component.service import serviceManager
+from zope.component.exceptions import ComponentLookupError
+from zope.proxy import removeAllProxies
+from zope.security.proxy import trustedRemoveSecurityProxy
+from zope.app.traversing.interfaces import IContainmentRoot
+from zope.app.location.interfaces import ILocation
+from zope.app.location import locate
+from zope.component.servicenames import Presentation
+from zope.interface import Interface
+import warnings
+import zope.thread
+
+siteinfo = zope.thread.local()
+
+def setSite(site=None):
+    if site is None:
+        siteinfo.services = None
+    else:
+        siteinfo.services = trustedRemoveSecurityProxy(site.getSiteManager())
+
+def getSite():
+    try:
+        services = siteinfo.services
+    except AttributeError:
+        services = siteinfo.services = None
+
+    if services is None:
+        return None
+
+    return services.__parent__
+
+
+def getServices_hook(context=None):
+
+    if context is None:
+        try:
+            services = siteinfo.services
+        except AttributeError:
+            services = siteinfo.services = None
+
+        if services is None:
+            return serviceManager
+
+        return services
+
+    try:
+        # This try-except is just backward compatibility really
+        return trustedRemoveSecurityProxy(getAdapter(context, IServiceService))
+    except ComponentLookupError:
+        # Deprecated support for a context that isn't adaptable to
+        # IServiceService.  Return the default service manager.
+        ## warnings.warn("getServices' context arg must be None or"
+        ##               "  adaptable to IServiceService.",
+        ##               DeprecationWarning, warningLevel())
+        return serviceManager
+
+
+def queryView(object, name, request, default=None,
+              providing=Interface, context=None):
+    # XXX test
+    #if context is None:
+    #    context = object
+    views = getService(Presentation, context)
+    view = views.queryView(object, name, request, default=default,
+                           providing=providing)
+    if ILocation.providedBy(view):
+        locate(view, object, name)
+
+    return view