Python中修改自定义模块后是否必须重新加载才能生效？

Hey there! Great observation on the differing behaviors when modifying your custom module—let's break down what's happening here, since it ties into both Python's core import rules and Spyder's handy (but easy to miss) auto-reload feature.

Why Your Test Showed Mixed Results #

First, let's unpack your specific scenario:

• Modifying function code worked without reimporting: This is because Spyder (and IPython, which powers Spyder's console) has a default auto-reload feature enabled. It quietly checks if your module files have changed before running your code, and automatically reloads them in the background. That's why your updated plus5 logic kicked in immediately without you doing anything extra.
• Renaming the function required a reimport: Auto-reload excels at updating existing objects (like changing what plus5 returns), but it doesn't always sync new or renamed names to the already-imported module reference in your namespace. When you first ran import test as t, the t variable got bound to the module's initial state—renaming the function creates a new name in the module that your existing t reference doesn't pick up automatically.

What Python's Official Docs Mean #

The note you found is 100% accurate for standard Python interpreters (without auto-reload tools):

Note: For efficiency reasons, each module is only imported once per interpreter session. Therefore, if you change your modules, you must restart the interpreter – or, if it’s just one module you want to test interactively, use importlib.reload()
e.g. import importlib; importlib.reload(modulename).

In a plain Python shell, you'd have to manually reload or restart to see any module changes. Spyder just adds that auto-reload layer to make interactive development smoother.

How to Control Reloads Manually #

If you want to take full control, or work in an environment without auto-reload:

• Use importlib.reload(): After modifying your module, run import importlib; importlib.reload(t) (where t is your imported module object). This refreshes the module in-place, so subsequent calls to t.plus5() will use the updated code.
• Restart the interpreter: For big changes (like adding/removing multiple functions/classes), restarting your Spyder console or Python session is the most reliable way to avoid weird state issues.

If you ever want to turn off Spyder's auto-reload, you can find the setting under Tools > Preferences > Python Interpreter and uncheck "Automatic reloading of modules".

内容的提问来源于stack exchange，提问作者gnikol