IPython自动完成正在调用__getattr __

Question

感谢您抽出宝贵的时间阅读本文档。希望在这个陌生的时代一切都好。

我正在实现一个类，并开始研究如何在其属性上提供自动完成功能。通过我的在线研究，我得出的结论是ipython补全来自__dir__方法。

__getattr__通常在您访问不存在的属性时调用。在我的项目中，如果发生这种情况，则需要一段时间。为什么ipython尝试访问属性而不是仅显示返回的__dir__？

from time import sleep

class example:
    def __getattr__(self, attr):
        if attr == 'test':
            sleep(2)

    def __dir__(self):
        return ["test"]

example. # press tab for auto complete

需要2秒。为什么会这样呢？自动完成功能应仅调用__dir__，但也应调用__getattr__。谢谢您的宝贵时间，请注意安全！

Answer 1

我认为问题是您需要一个类的实例。这些方法是实例方法。

class Example:
    def __init__(self):
        # Set some arbitrary attributes on the instance.
        self.bar = "bar"
        self.baz = "baz"

    def __getattr__(self, attr):
        # print is a more reliable indication that the
        # method was called. sleep was probably perceived but not
        # happening.
        print(f"__getattr__ called: {attr}")
        # prevent recursion by using the __getattribute__ on parent.
        return super().__getattribute__(attr)

    def __dir__(self):
        # This seems to be the method called when tab key is hit.
        return ["footest"]

# Create an instance of Example.
# The instance methods can then be called on the instance.

example = Example()
example.bar
example.<tab> # "footest" displayed