import quickfix

class MyStringField(quickfix.StringField):
	def __init__(self, data = None)
		if data == None:
			quickfix.StringField.__init__(self, 6123)
		else:
			quickfix.StringField.__init__(self, 6123, data)

class MyPriceField(quickfix.DoubleField):
	def __init__(self, data = None)
		if data == None:
			quickfix.DoubleField.__init__(self, 8756)
		else:
			quickfix.DoubleField.__init__(self, 8756, data)