Django 源码中
django.conf.init.py 中
class SettingsReference(str): """ String subclass which references a current settings value. It's treated as the value in memory but serializes to a settings.NAME attribute reference. """ def __new__(self, value, setting_name): return str.__new__(self, value) def __init__(self, value, setting_name): self.setting_name = setting_name__new__的第一个参数是 self，为什么不是cls？
