循環導入：在Python Imports的領域中，了解Python

中的行為，遇到模塊試圖彼此導入的模塊可能導致令人困惑的情況的情況。本文深入研究了Python中相互和循環（環狀）導入的複雜性，解釋了它們的複雜性並提供了真實的例子來說明其行為。

Complications with Circular Imports

However, issues arise when using the from ... import statement within circular imports. Consider the following scenario: module A imports a symbol from module B, which in turn imports a symbol from module A. This circular dependency creates a situation where each module requires the other to be fully loaded before it can complete its own import.

Fatal Circular Imports

Unfortunately, this type of dependency can result in an ImportError or attributeError異常。 The underlying cause is that the interpreter attempts to recursively import the same module, leading to a stack overflow.

Nonfatal Circular Imports

Despite the aforementioned issues, there exist scenarios where circular imports can coexist harmoniously, as demonstrated in the examples outlined in the original question. These exceptions typically involve combinations of top-level imports, relative imports, and importing specific attributes rather than entire modules.

Conclusion

While circular imports in Python can be inherently problematic, understanding their nuances and employing the appropriate import strategies can help developers navigate these intricate situations effectively.通過遵守這些準則，可以利用循環導入來實現所需的功能，而不會遇到任何陷阱。