Question

我正在阅读有关静态变量（即类变量），静态方法，类方法以及所有这些变量的细微差别。在像C ++这样的语言中，static variables are generally strongly discouraged because of many IMO compelling reasons。我只是好奇，如果Python社区对静态变量的已知位置不鼓励。 The Google Python Style Guide does not seem to have a pro/con position on static variables

在Python语言中，不鼓励静态变量（即代码异味）？

谷歌C ++风格指南的声明“[静态变量]导致难以发现的错误”当然不仅适用于C ++语言，也适用于Python语言。

Answer 1

在某些语言（如Java）中，静态变量可能会导致可测试性问题，因为它们无法轻易模拟出来。这在Python中并非如此。

但是，静态和类变量的好处较少，因为当您拥有不需要访问特定实例成员的值或函数时，您可以在模块级别定义它们，并在不使用它们的情况下使用它们引用一个类 - 一种像Java这样的语言不具备的奢侈品。

所以我会说static本身并不是代码气味。但如果你的一半变量是static，那么我会问一些关于你对OO设计理解的问题。

Answer 2

您正在阅读的C ++资源正在讨论类型为static storage duration的变量。那些与静态变量不同;例如，以下变量也具有静态存储持续时间：

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这些在C ++中很危险，因为它们的初始化和销毁顺序是不可预测的，容易出错。

Python没有静态存储持续时间的变量。它根本没有存储持续时间。它具有（模块）全局变量和静态变量，但它们的初始化顺序比C ++中的定义要精确得多。除非你有循环导入，否则不太可能发生C ++问题，即使这样，循环导入也是问题，而不是全局变量或静态变量。

也就是说，可变的全局状态，例如你在程序过程中发生变异的全局变量或静态变量，对于language-independent reasons是不好的。这与C ++具有静态存储持续时间的问题完全不同。你不打算变异的全局变量和静态变量通常很好。

Python：劝阻静态变量？

2 个答案: