[Zope3-checkins] CVS: Zope3/src/zodb/query - relation.py:1.1.2.4

[Jeremy Hylton]

Update of /cvs-repository/Zope3/src/zodb/query
In directory cvs.zope.org:/tmp/cvs-serv14534

Modified Files:
      Tag: jeremy-query-branch
	relation.py 
Log Message:
Redefine many2many function as join() + arity() setters.


=== Zope3/src/zodb/query/relation.py 1.1.2.3 => 1.1.2.4 ===
--- Zope3/src/zodb/query/relation.py:1.1.2.3	Fri Apr 25 19:24:24 2003
+++ Zope3/src/zodb/query/relation.py	Mon Apr 28 11:48:21 2003
@@ -84,12 +84,13 @@
     def setclass(self, cls):
         self.cls = cls
 
-    def register(self, other, many):
+    def register(self, other):
+        if self.many is None:
+            raise ValueError, "must define arity first"
         # Called by many2many below to establish connection
         # between two Relation objects.
         self.other = other
         self.name = find_attribute_name(other)
-        self.many = many
         # XXX This is the wrong name!  It's the name of the other
         # descriptor.
         self.attr = "_r_" + self.name
@@ -111,10 +112,17 @@
             if r == v.manager:
                 return name
 
-def many2many(r1, r2):
-    """Connect two Relations in a many-to-many relationship."""
-    r1.register(r2, True)
-    r2.register(r1, True)
+def one(r):
+    r.many = False
+    return r
+
+def many(r):
+    r.many = True
+    return r
+
+def join(r1, r2):
+    r1.register(r2)
+    r2.register(r1)
 
 class SoftwareProject(object):
 
@@ -135,8 +143,9 @@
 
     def __repr__(self):
         return "%s(%r)" % (self.__class__.__name__, self.name)
-    
-many2many(SoftwareProject.developers, Developer.projects)
+
+join(many(SoftwareProject.developers),
+     many(Developer.projects))
 
 if __name__ == "__main__":
     zope3 = SoftwareProject("Zope3")