[Checkins] SVN: zope.globalrequest/trunk/src/zope/globalrequest/ provide a way to store request objects in a thread-local manner[*] and register event subscribers to set and clear the values

[Andreas Zeidler]

Log message for revision 94753:
  provide a way to store request objects in a thread-local manner[*] and register event subscribers to set and clear the values
  
  [*] borrowing the [http://dev.plone.org/collective/browser/collective.solr/trunk/collective/solr/local.py?rev=78873 local.py] module
  from [http://pypi.python.org/pypi/collective.solr/ collective.solr]

Changed:
  U   zope.globalrequest/trunk/src/zope/globalrequest/README.txt
  U   zope.globalrequest/trunk/src/zope/globalrequest/__init__.py
  A   zope.globalrequest/trunk/src/zope/globalrequest/configure.zcml
  A   zope.globalrequest/trunk/src/zope/globalrequest/local.py
  A   zope.globalrequest/trunk/src/zope/globalrequest/subscribers.py

-=-
Modified: zope.globalrequest/trunk/src/zope/globalrequest/README.txt
===================================================================
--- zope.globalrequest/trunk/src/zope/globalrequest/README.txt	2009-01-15 15:47:39 UTC (rev 94752)
+++ zope.globalrequest/trunk/src/zope/globalrequest/README.txt	2009-01-15 15:47:46 UTC (rev 94753)
@@ -24,10 +24,16 @@
 
   >>> from zope.interface import implements
   >>> from zope.globalrequest import ftests
+  >>> from zope.globalrequest import getRequest
   >>> class Foo(object):
   ...     implements(ftests.IFoo)
   ...     def foo(self):
-  ...         return 'foo!'
+  ...         request = getRequest()
+  ...         if request:
+  ...             name = request.get('name', 'n00b')
+  ...         else:
+  ...             name = 'foo'
+  ...         return 'y0 %s!' % name
 
 Unfortunately the utility class cannot be directly imported from here, i.e.
 relatively, so we have to make it available from somewhere else to register
@@ -43,9 +49,33 @@
   ... </configure>
   ... """)
 
-Rendering the view again should now give us the value provided by the utility:
+Rendering the view again should now give us the default value provided by the
+utility:
 
   >>> browser.reload()
   >>> browser.contents
-  'foo!'
+  'y0 foo!'
 
+Up to now the request hasn't been stored for us yet, so let's hook up the
+necessary event subscribers and try that again:
+
+  >>> zcml("""
+  ... <configure xmlns="http://namespaces.zope.org/zope">
+  ...   <include package="zope.component" file="meta.zcml" />
+  ...   <include package="zope.globalrequest" />
+  ... </configure>
+  ... """)
+
+Now we should get the request and therefore the fallback value from the form
+lookup:
+
+  >>> browser.reload()
+  >>> browser.contents
+  'y0 n00b!'
+
+If we now provide a request value we should be greeted properly:
+
+  >>> browser.open('?name=d4wg!')
+  >>> browser.contents
+  'y0 d4wg!!'
+

Modified: zope.globalrequest/trunk/src/zope/globalrequest/__init__.py
===================================================================
--- zope.globalrequest/trunk/src/zope/globalrequest/__init__.py	2009-01-15 15:47:39 UTC (rev 94752)
+++ zope.globalrequest/trunk/src/zope/globalrequest/__init__.py	2009-01-15 15:47:46 UTC (rev 94753)
@@ -3,3 +3,21 @@
 
 moduleProvides(IGlobalRequest)
 
+
+from zope.globalrequest.local import getLocal, setLocal
+
+
+def getRequest():
+    """ return the currently active request object """
+    return getLocal('request')
+
+
+def setRequest(request):
+    """ set the request object to be returned by `getRequest` """
+    setLocal('request', request)
+
+
+def clearRequest():
+    """ clear the stored request object """
+    setRequest(None)
+

Added: zope.globalrequest/trunk/src/zope/globalrequest/configure.zcml
===================================================================
--- zope.globalrequest/trunk/src/zope/globalrequest/configure.zcml	                        (rev 0)
+++ zope.globalrequest/trunk/src/zope/globalrequest/configure.zcml	2009-01-15 15:47:46 UTC (rev 94753)
@@ -0,0 +1,16 @@
+<configure
+    xmlns="http://namespaces.zope.org/zope"
+    i18n_domain="zope.globalrequest">
+
+  <subscriber
+    handler=".subscribers.set"
+    for="zope.app.component.interfaces.ISite
+         zope.app.publication.interfaces.IBeforeTraverseEvent"
+    trusted="y" />
+
+  <subscriber
+    handler=".subscribers.clear"
+    for="zope.app.publication.interfaces.IEndRequestEvent"
+    trusted="y" />
+
+</configure>

Added: zope.globalrequest/trunk/src/zope/globalrequest/local.py
===================================================================
--- zope.globalrequest/trunk/src/zope/globalrequest/local.py	                        (rev 0)
+++ zope.globalrequest/trunk/src/zope/globalrequest/local.py	2009-01-15 15:47:46 UTC (rev 94753)
@@ -0,0 +1,18 @@
+from threading import local
+
+
+# a thread-local object holding arbitrary data
+localData = local()
+marker = []
+
+# helper functions to get/set local values or optionally initialize them
+def getLocal(name, factory=lambda: None):
+    value = getattr(localData, name, marker)
+    if value is marker:
+        value = factory()
+        setLocal(name, value)
+    return value
+
+def setLocal(name, value):
+    setattr(localData, name, value)
+

Added: zope.globalrequest/trunk/src/zope/globalrequest/subscribers.py
===================================================================
--- zope.globalrequest/trunk/src/zope/globalrequest/subscribers.py	                        (rev 0)
+++ zope.globalrequest/trunk/src/zope/globalrequest/subscribers.py	2009-01-15 15:47:46 UTC (rev 94753)
@@ -0,0 +1,12 @@
+from zope.globalrequest import setRequest, clearRequest
+
+
+def set(context, event):
+    """ set the request object as provided by the event """
+    setRequest(event.request)
+
+
+def clear(event):
+    """ clear the stored request object """
+    clearRequest()
+