__getattr__和__getattribute__之间的区别 [英] Difference between __getattr__ vs __getattribute__

问题描述

我试图了解何时使用__getattr__或__getattribute__. 文档提及__getattribute__适用于新样式类.什么是新型类?

__getattr__和__getattribute__之间的主要区别在于，仅当找不到通常的属性时才调用__getattr__.这对于实现缺少属性的后备方法很有用，并且可能是您想要的两个之一.

在查看对象的实际属性之前，将调用

__getattribute__，因此正确实现可能会比较棘手.您可以非常轻松地进行无限递归.

新式类是从object派生的，旧式类是Python 2.x中没有显式基类的类.但是，在__getattr__和__getattribute__之间进行选择时，旧样式类与新样式类之间的区别并不是很重要.

您几乎可以肯定想要__getattr__.

I am trying to understand when to use __getattr__ or __getattribute__. The documentation mentions __getattribute__ applies to new-style classes. What are new-style classes?

解决方案

A key difference between __getattr__ and __getattribute__ is that __getattr__ is only invoked if the attribute wasn't found the usual ways. It's good for implementing a fallback for missing attributes, and is probably the one of two you want.

__getattribute__ is invoked before looking at the actual attributes on the object, and so can be tricky to implement correctly. You can end up in infinite recursions very easily.

New-style classes derive from object, old-style classes are those in Python 2.x with no explicit base class. But the distinction between old-style and new-style classes is not the important one when choosing between __getattr__ and __getattribute__.

You almost certainly want __getattr__.

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