Reloading submodules in IPython

Currently I am working on a python project that contains sub modules and uses numpy/scipy. Ipython is used as interactive console. Unfortunately I am not very happy with workflow that I am using right now, I would appreciate some advice.

In IPython, the framework is loaded by a simple import command. However, it is often necessary to change code in one of the submodules of the framework. At this point a model is already loaded and I use IPython to interact with it.

Now, the framework contains many modules that depend on each other, i.e. when the framework is initially loaded the main module is importing and configuring the submodules. The changes to the code are only executed if the module is reloaded using reload(main_mod.sub_mod). This is cumbersome as I need to reload all changed modules individually using the full path. It would be very convenient if reload(main_module) would also reload all sub modules, but without reloading numpy/scipy..

Solution 1:

IPython comes with some automatic reloading magic:

%load_ext autoreload
%autoreload 2

It will reload all changed modules every time before executing a new line. The way this works is slightly different than dreload. Some caveats apply, type %autoreload? to see what can go wrong.

If you want to always enable this settings, modify your IPython configuration file ~/.ipython/profile_default/ipython_config.py[1] and appending:

c.InteractiveShellApp.extensions = ['autoreload']     
c.InteractiveShellApp.exec_lines = ['%autoreload 2']

Credit to @Kos via a comment below.

[1] If you don't have the file ~/.ipython/profile_default/ipython_config.py, you need to call ipython profile create first. Or the file may be located at $IPYTHONDIR.

Solution 2:

In IPython 0.12 (and possibly earlier), you can use this:

%load_ext autoreload
%autoreload 2

This is essentially the same as the answer by pv., except that the extension has been renamed and is now loaded using %load_ext.

Solution 3:

Module named importlib allow to access to import internals. Especially, it provide function importlib.reload():

import importlib
importlib.reload(my_module)

In contrary of %autoreload, importlib.reload() also reset global variables set in module. In most cases, it is what you want.

importlib is only available since Python 3.1. For older version, you have to use module imp.

I suggest to read documentation of importlib.reload() to get the list of all caveats of this function (recursive reload, cases where definitions of old objects remain, etc...).