How to use lambda as method within a class?

Use lambda self, x: "...%s..." % x

You have few possibilities of using/accessing class variables of lambdas. Three of them are:

class BaseClass(object):
    successify = lambda x: "<Success>%s</Success>" % x
    errorify = lambda x: "<Error>%s</Error>" % x
    def try1(self):
        print(self.__class__.successify("try1"))
    def try2(self):
        print(self.__class__.successify("try2"))

 # or 

class BaseClass(object):
    successify = lambda x: "<Success>%s</Success>" % x
    errorify = lambda x: "<Error>%s</Error>" % x
    def try1(self):
        print(BaseClass.successify("try1"))
    def try2(self):
        print(BaseClass.successify("try2"))

# or Please not changes to lambda definitions below

class BaseClass(object):
    successify = lambda self,x: "<Success>%s</Success>" % x
    errorify = lambda self,x: "<Error>%s</Error>" % x
    def try1(self):
        print(self.successify("try1"))
    def try2(self):
        print(self.successify("try2"))