为什么getattr()比self慢得多.__ dict __.get()？

Question

以下示例来自Python 2.7上的REST数据库驱动程序.

在__setattr__下面的方法中,如果我使用注释掉的getattr()行,它会将对象实例化性能从600 rps降低到230.

为什么getattr()比self.__dict__.get()这种情况慢得多？

class Element(object):

    def __init__(self, client):
        self._client = client
        self._data = {}
        self._initialized = True

    def __setattr__(self, key, value):
        #_initialized = getattr(self, "_initialized", False)
        _initialized = self.__dict__.get("_initialized", False)
        if key in self.__dict__ or _initialized is False:
            # set the attribute normally
            object.__setattr__(self, key, value)
        else:
            # set the attribute as a data property
            self._data[key] = value

Answer 1

简而言之:因为getattr(foo,bar) 同样的事情foo.bar,这与访问该__dict__属性不同(为了一个开始,getattr必须选择正确的__dict__,但还有更多的事情发生).

此处包含或链接的详细信息:http://docs.python.org/reference/datamodel.html(搜索"getattr").