"%(name)s" % {"name":"school"}     "school"  #命名式


"student"%{"name":"school"}   "student"  # 注意：不报错

"student" % "school"   #报错

"%s" % "teacher" "teacher" #常用写法



"%(num).2f" % {"num":2.1234}   2.12   # 命名式

"%.2f" % {"num":2.1234}  #报错      # 注意：报错了。。。。

"%.2f" % 2.12345  2.12  #常用写法

if self.redis_key is None:
            self.redis_key = settings.get(
                ‘REDIS_START_URLS_KEY‘, defaults.START_URLS_KEY,
            )
self.redis_key = self.redis_key % {‘name‘: self.name}