Triggers should be dropped before the corresponding functions.

 * pyrseas/database.py (Database.diff_map): Add call to
   functions._drop.
 * pyrseas/dbobject/function.py (ProcDict.diff_map): Only mark
   functions for dropping.  (ProcDict._drop): New function to actually
   drop the functions.

pyrseas/database.py

@@ -144,5 +144,6 @@ def diff_map(self, input_map):
         stmts.append(self.db.triggers.diff_map(self.ndb.triggers))
         stmts.append(self.db.rules.diff_map(self.ndb.rules))
         stmts.append(self.db.schemas._drop())
+        stmts.append(self.db.functions._drop())
         stmts.append(self.db.languages._drop())
         return [s for s in flatten(stmts)]

pyrseas/dbobject/function.py

@@ -261,10 +261,22 @@ def diff_map(self, infuncs):
         # check existing functions
         for (sch, fnc, arg) in self.keys():
             func = self[(sch, fnc, arg)]
-            # if missing, drop them
+            # if missing, mark it for dropping
             if (sch, fnc, arg) not in infuncs:
-                    stmts.append(func.drop())
+                func.dropped = False
 
         if created:
             stmts.insert(0, "SET check_function_bodies = false")
         return stmts
+
+    def _drop(self):
+        """Actually drop the functions
+
+        :return: SQL statements
+        """
+        stmts = []
+        for (sch, fnc, arg) in self.keys():
+            func = self[(sch, fnc, arg)]
+            if hasattr(func, 'dropped'):
+                stmts.append(func.drop())
+        return stmts