Add clone() methods.

James William Pye · James William Pye · commit d214f737df4b · 2009-05-17T17:45:23.000-07:00
diff --git a/postgresql/api.py b/postgresql/api.py
@@ -287,6 +287,12 @@ class Cursor(
 		False : 'BACKWARD',
 	}
 
+	@abstractmethod
+	def clone(self) -> "Cursor":
+		"""
+		Create a new cursor using the same factors as `self`.
+		"""
+
 	def __iter__(self):
 		return self
 
@@ -461,6 +467,15 @@ def parameter_types(self) -> [type]:
 			[<class 'int'>, <class 'str'>]
 		"""
 
+	@abstractmethod
+	def clone(self) -> "PreparedStatement":
+		"""
+		Create a new statement object using the same factors as `self`.
+
+		When used for refreshing plans, the new clone should replace references to
+		the original.
+		"""
+
 	@abstractmethod
 	def __call__(self, *parameters : "Positional Parameters") -> ["Row"]:
 		"""
@@ -1167,6 +1182,13 @@ def closed(self) -> bool:
 		True
 		"""
 
+	@abstractmethod
+	def clone(self) -> "Connection":
+		"""
+		Create another connection using the same factors as `self`. The returned
+		object should be open and ready for use.
+		"""
+
 	def connect(self) -> None:
 		"""
 		Establish the connection to the server and initialize the category.
diff --git a/postgresql/driver/pq3.py b/postgresql/driver/pq3.py
@@ -480,6 +480,9 @@ def _e_metas(self):
 		yield ('direction', 'FORWARD' if self.direction else 'BACKWORD')
 		yield ('type', 'Cursor')
 
+	def clone(self):
+		return type(self)(self.statement, self.parameters, self.database, None)
+
 	def __init__(self, statement, parameters, database, cursor_id):
 		self.database = database or statement.database
 		self.statement = statement
@@ -667,6 +670,12 @@ def _e_metas(self):
 		elif ct is not None:
 			yield ('sql_column_types', ct)
 
+	def clone(self):
+		ps = type(self)(self.database, None, self.string)
+		ps._init()
+		ps._fini()
+		return ps
+
 	def __init__(self, database, statement_id, string):
 		self.database = database
 		self.statement_id = statement_id or ID(self)
@@ -2074,6 +2083,11 @@ def _receive_async(self, msg, controller = None):
 				creator = c
 			).raise_message()
 
+	def clone(self, *args, **kw):
+		c = type(self)(self.connector, *args, **kw)
+		c.connect()
+		return c
+
 	def __init__(self, connector, *args, **kw):
 		"""
 		Create a connection based on the given connector.
diff --git a/postgresql/test/test_driver.py b/postgresql/test/test_driver.py
@@ -330,6 +330,31 @@ def raise_exc(l):
 				raise v
 		self.failUnlessRaises(pg_exc.QueryCanceledError, raise_exc, rl)
 
+	def testClones(self):
+		self.db.execute('create table _can_clone_see_this (i int);')
+		try:
+			with self.db.clone() as db2:
+				self.failUnlessEqual(db2.prepare('select 1').first(), 1)
+				self.failUnlessEqual(db2.prepare(
+						"select count(*) FROM information_schema.tables " \
+						"where table_name = '_can_clone_see_this'"
+					).first(), 1
+				)
+		finally:
+			self.db.execute('drop table _can_clone_see_this')
+		# check already open
+		db = self.db.clone()
+		self.failUnlessEqual(db.prepare('select 1').first(), 1)
+		db.close()
+
+		ps = self.db.prepare('select 1')
+		ps2 = ps.clone()
+		self.failUnlessEqual(ps2.first(), ps.first())
+		ps2.close()
+		c = ps.declare()
+		c2 = c.clone()
+		self.failUnlessEqual(c.read(), c2.read())
+
 	def testItsClosed(self):
 		ps = self.db.prepare("SELECT 1")
 		# If scroll is False it will pre-fetch, and no error will be thrown.
