ipython中的模块导入机制

Python REPL中的模块导入机制

• How does importing in Python work?

Turns out that, for efficiency reasons, when you import a module in an interactive Python session, Python interpreter does two steps:

1. First, it checks if the module is already cached in the sys.module
   dictionary.

2. And only if it’s not there, it actually imports the
   module

Another one of the magic methods in IPython is related to reloading modules. It’s called %autoreload. It’s not enabled by default, so you have to load it as an extension:

%autoreload 0 - disables the auto-reloading. This is the default setting.
%autoreload 1 - it will only auto-reload modules that were imported using the %aimport function (e.g %aimport my_module). It’s a good option if you want to specifically auto-reload only a selected module.
%autoreload 2 - auto-reload all the modules. Great way to make writing and testing your modules much easier.