python中type的构造函数参数含义说明

测试代码如下:

代码如下:

class modelmetaclass(type):
def __new__(cls,name,base,attrs):
logging.info(“cls is:”+str(cls))
logging.info(“name is:”+str(name))
logging.info(“base is:”+str(base))
logging.info(“attrs is:”+str(attrs))
return type.__new__(cls,name,base,attrs)
pass
pass

class model(dict):
__metaclass__ = modelmetaclass
def __init__(self):
pass
pass

def main():
m=model()

if __name__ == ‘__main__’:
main()

测试结果:

代码如下:

info:root:cls is:
info:root:name is:model
info:root:base is:(,)
info:root:attrs is:{‘__module__’: ‘__main__’, ‘__metaclass__’: , ‘__init__’: }

结论就显而易见了。cls是当前类的名字,即类本身。name是通过__metaclass__属性指向modelmetaclass的类,即要实例化的类,modelmetaclass拦截了该类的实例化。base是要实例化的类的基类。attrs是要实例化的类的属性集合。

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