为什么在python中修改本地人不是个好主意? [英] Why is it bad idea to modify locals in python?

问题描述

与该回复相关的此处.

Related to this reply here. Locals' doc here.

文档提到字典不应更改，不确定其含义，但是locals()是否适用于数据不会更改的实验室报告，例如在测量中?

The docs mention that the dictionary should not change, not sure what it means but would locals() be applicable in lab-reports where data won't change, for example in measurements?

推荐答案

修改是一个坏主意，因为文档(您链接到该文档)明确表示不:

Modification is a bad idea because the documentation (which you link) explicitly says not to:

注意:请勿修改此词典的内容；更改可能不会影响解释器使用的局部变量和自由变量的值.

Note: The contents of this dictionary should not be modified; changes may not affect the values of local and free variables used by the interpreter.

除了这些，您不需要任何其他原因.

You don't need any more reason than that.

如果您以不修改任何变量的方式使用它，那么您会没事的，但是我会质疑设计，看看是否有更好的方法来做您想要的事情.

If you are using it in a way that doesn't modify any variables, then you'll be fine, but I'd question the design and see if there's a better way to do what you want.

在您链接的特定示例中，当在模块的全局范围内使用locals时，locals实际上是globals().这种非常具体的用法现在可以使用，尽管我希望它可以像全局变量一样继续使用，但您最好也可以使用全局变量.

In the specific example you link, locals is actually globals(), as you use it in the global scope of a module. This very specific use works now and, though I expect it to continue to work just as with globals, you might as well just use globals instead.

一个更干净的解决方案可能是在不知道其余设计的情况下，对变量使用常规的ol'字典；然后使用data ["x"] =值，而不是globals()["x"] =值.

An even cleaner solution is probably, without knowing the rest of your design, to use a regular ol' dictionary for your variables; then use data["x"] = value instead of globals()["x"] = value.

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