Define _begin to define a commit hook on Zope 2.8.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@4456 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/SQLCatalog.py

@@ -102,6 +102,15 @@ class UidBuffer(TM):
     self.finished_buffer = []
     self.allocated_buffer = {}
     
+  def _begin(self, *ignored):
+    # In Zope 2.8 (ZODB 3.4), use beforeCommitHook instead of
+    # patching Trasaction.
+    transaction = get_transaction()
+    try:
+      transaction.beforeCommitHook(self.tpc_prepare, transaction)
+    except AttributeError:
+      pass
+    
   def tpc_prepare(self, transaction, sub=None):
     """Mark used uids."""
     tid = get_ident()