How to import all submodules?

Question

I have a directory structure as follows:

| main.py
| scripts
|--| __init__.py
   | script1.py
   | script2.py
   | script3.py

From main.py, the module scripts is imported. I tried using pkgutils.walk_packages in combination with __all__, but using that, I can only import all the submodules directly under main using from scripts import *. I would like to get them all under scripts. What would be the cleanest way to import all the submodules of scripts so that I could access scripts.script1 from main?

EDIT: I am sorry that I was a bit vague. I would like to import the submodules on run-time without specifying them explicitly in __init__.py. I can use pkgutils.walk_packages to get the submodule names (unless someone knows of a better way), but I am not sure of the cleanest way to use these names (or maybe the ImpImporters that walk_packages returns?) to import them.

Answer 1

I've played around with Joe Kington's Answer and have built a solution that uses globals and get/setattr and thus doesn't need eval. A slight modification is that instead of directly using the packages __path__ for walk_packages, I use the packages parent directory and then only import modules starting with __name__ + ".". This was done to reliably get all subpackages from walk_packages - in my use case I had a subpackage named test which caused pkgutil to iterate over the test package from python's library; furthermore, using __path__ would not recurse into the packages subdirectories. All these issues were observed using jython and python2.5, the code below is only tested in jython thus far.

Also note that OPs question only talks about importing all modules from a package, this code recursively imports all packages too.

from pkgutil import walk_packages
from os import path

__all__ = []
__pkg_prefix = "%s." % __name__
__pkg_path = path.abspath(__path__[0]).rsplit("/", 1)[0] #parent directory

for loader, modname, _ in walk_packages([__pkg_path]):
    if modname.startswith(__pkg_prefix):
        #load the module / package
        module = loader.find_module(modname).load_module(modname)
        modname = modname[len(__pkg_prefix):] #strip package prefix from name
        #append all toplevel modules and packages to __all__
        if not "." in modname:
            __all__.append(modname)
            globals()[modname] = module
        #set everything else as an attribute of their parent package
        else:
            #get the toplevel package from globals()
            pkg_name, rest = modname.split(".", 1)
            pkg = globals()[pkg_name]
            #recursively get the modules parent package via getattr
            while "." in rest:
                subpkg, rest = rest.split(".", 1)
                pkg = getattr(pkg, subpkg)
            #set the module (or package) as an attribute of its parent package
            setattr(pkg, rest, module)

As a future improvement I'll try to make this dynamic with a __getattr__ hook on the package, so the actual modules are only imported when they are accessed...

Answer 2

This is based on the answer that kolypto provided, but his answer does not perform recursive import of packages, whereas this does. Although not required by the main question, I believe recursive import applies and can be very useful in many similar situations. I, for one, found this question when searching on the topic.

This is a nice, clean way of performing the import of the subpackage's modules, and should be portable as well, and it uses the standard lib for python 2.7+ / 3.x.

import importlib
import pkgutil


def import_submodules(package, recursive=True):
    """ Import all submodules of a module, recursively, including subpackages

    :param package: package (name or actual module)
    :type package: str | module
    :rtype: dict[str, types.ModuleType]
    """
    if isinstance(package, str):
        package = importlib.import_module(package)
    results = {}
    for loader, name, is_pkg in pkgutil.walk_packages(package.__path__):
        full_name = package.__name__ + '.' + name
        results[full_name] = importlib.import_module(full_name)
        if recursive and is_pkg:
            results.update(import_submodules(full_name))
    return results

Usage:

# from main.py, as per the OP's project structure
import scripts
import_submodules(scripts)

# Alternatively, from scripts.__init__.py
import_submodules(__name__)

Answer 3

I was writing a small personal library and adding new modules all the time so I wrote a shell script to look for scripts and create the __init__.py's. The script is executed just outside of the main directory for my package, pylux.

I know it probably isn't the answer you're looking for, but it servered its purpose for me and it might be useful to someone else, too.

#!/bin/bash

echo 'Traversing folder hierarchy...'

CWD=`pwd`


for directory in `find pylux -type d -exec echo {} \;`;
do
    cd $directory
    #echo Entering $directory
    echo -n "" > __init__.py

    for subdirectory in `find . -type d -maxdepth 1 -mindepth 1`;
    do
        subdirectory=`echo $subdirectory | cut -b 3-`
        #echo -n '    ' ...$subdirectory
        #echo -e '\t->\t' import $subdirectory
        echo import $subdirectory >> __init__.py
    done

    for pyfile in *.py ;
    do
        if [ $pyfile = $(echo __init__.py) ]; then
            continue
        fi
        #echo -n '    ' ...$pyfile
        #echo -e '\t->\t' import `echo $pyfile | cut -d . -f 1`
        echo import `echo $pyfile | cut -d . -f 1` >> __init__.py
    done
    cd $CWD

done


for directory in `find pylux -type d -exec echo {} \;`;
do
    echo $directory/__init__.py:
    cat $directory/__init__.py | awk '{ print "\t"$0 }'
done

Answer 4

I got tired of this problem myself, so I wrote a package called automodinit to fix it. You can get it from http://pypi.python.org/pypi/automodinit/. Usage is like this:

1. Include the automodinit package into your setup.py dependencies.
2. Add the following to the beginning of the __init__.py file:

__all__ = ["I will get rewritten"]
# Don't modify the line above, or this line!
import automodinit
automodinit.automodinit(__name__, __file__, globals())
del automodinit
# Anything else you want can go after here, it won't get modified.

That's it! From now on importing a module will set __all__ to a list of .py[co] files in the module and will also import each of those files as though you had typed:

for x in __all__: import x

Therefore the effect of from M import * matches exactly import M.

automodinit is happy running from inside ZIP archives and is therefore ZIP safe.

Answer 5

In Python 3, you can put the following code in your scripts.__init__.py file:

import os
import os.path as op

__all__ = [
    op.splitext(f)[0]  # remove .py extension
    for f in os.listdir(BASE_DIR)  # list contents of current dir
    if not f.startswith('_') and
    ((op.isfile(op.join(BASE_DIR, f)) and f.endswith('.py')) or
     (op.isdir(op.join(BASE_DIR, f)) and op.isfile(op.join(BASE_DIR, f, '__init__.py'))))
]

from . import *  # to make `scripts.script1` work after `import script`

For more info about Python imports, I recommend David Beazley's talk at PyCon 2015: https://youtu.be/0oTh1CXRaQ0

Answer 6

Edit: Here's one way to recursively import everything at runtime...

(Contents of __init__.py in top package directory)

import pkgutil

__all__ = []
for loader, module_name, is_pkg in  pkgutil.walk_packages(__path__):
    __all__.append(module_name)
    _module = loader.find_module(module_name).load_module(module_name)
    globals()[module_name] = _module

I'm not using __import__(__path__+'.'+module_name) here, as it's difficult to properly recursively import packages using it. If you don't have nested sub-packages, and wanted to avoid using globals()[module_name], though, it's one way to do it.

There's probably a better way, but this is the best I can do, anyway.

Original Answer (For context, ignore othwerwise. I misunderstood the question initially):

What does your scripts/__init__.py look like? It should be something like:

import script1
import script2
import script3
__all__ = ['script1', 'script2', 'script3']

You could even do without defining __all__, but things (pydoc, if nothing else) will work more cleanly if you define it, even if it's just a list of what you imported.