CODEWITHSUNDEEP
python
user3645103
user3645103

Reputation:

How can I create a simple system wide python library?

I see there are some built in packages that I can import from any script like:

from datetime import date

today = date.today()
print today

How can I create a simple package and add it to the system library so that I can import it like datetime in the above example?

Upvotes: 10

Views: 8151

Answers (5)

Joel Cornett
Joel Cornett

Reputation: 24788

If you simply want the module for personal use, just drop it in a folder and add that folder to the PYTHONPATH environment variable.

For example, create a folder in your home directory called ~/python-packages, then add the following line to your .bashrc (assuming you are using bash):

 export PYTHONPATH=$HOME/python-packages`

Then, simply drop any modules/packages you want to make available in ~/python-packages.

Upvotes: 1

glibdud
glibdud

Reputation: 7840

The quick way, if you're just making something for your own use and not worrying about packaging, is to put the module (which could be as simple as a single file) in your system's site-packages directory. (On Debian-based systems, you probably want to use dist-packages instead).

To find out where your site-packages/dist-packages directory is, start Python and:

>>> from sys import path
>>> path
['', '/usr/lib/python3.4/site-packages/pip-7.1.2-py3.4.egg', '/usr/lib/python34.zip', '/usr/lib/python3.4', '/usr/lib/python3.4/plat-cygwin', '/usr/lib/python3.4/lib-dynload', '/usr/lib/python3.4/site-packages']

Note the last item in that example: /usr/lib/python3.4/site-packages. That's the sort of thing you're looking for. So in this example, if I save the following to /usr/lib/python3.4/site-packages/foo.py:

def bar():
    print('Hello world!')

Then from anywhere on my system:

>>> from foo import bar
>>> bar()
Hello world!

Upvotes: 7

ymbirtt
ymbirtt

Reputation: 1666

You're trying to make a module.

Start by installing the setuptools package; on either Windows or Linux you should be able to type pip install setuptools at a terminal to get that installed. You should now be able to write import setuptools at a python prompt without getting an error.

Once that's working, set up a directory structure containing a setup.py and a folder for your project's code to go in. The directory must contain a file called __init__.py, which allows you to import the directory as though it's a file.

some_folder/
|    setup.py
|    my_project/__init__.py

In setup.py, drop the following content:

# setup.py
from setuptools import setup

setup(name="My Awesome Project",
      version="0.0",
      packages=["my_project"])

In my_project/__init__.py, drop some stuff that you'd like to be able to import. Let's say...

# my_project/__init__.py
greeting = "Hello world!"

Now, in order to install the project at a system-wide level, run python setup.py install. Note that you'll need to run this as root if you're on Linux, since you're making changes to the system-wide python libraries.

After this, you should be able to run python from any directory you like and type:

>>> from my_project import greeting
>>> print greeting
Hello world!
>>>

Note that this is enough to tell you how to make a module, but there's one hell of a lot of stuff that setuptools can do for you. Take a look at https://pythonhosted.org/setuptools/setuptools.html for more info on building stuff, and https://docs.python.org/2/tutorial/modules.html for more info on how modules actually work. If you'd like to look at a package that (I hope) is reasonably simple, then I made my LazyLog module a couple of weeks ago on a train, and you're welcome to use it for reference.

Upvotes: 15

knh170
knh170

Reputation: 2990

If you really need a package, you can do it with boost, which allows interacts with C++. You may implement algorithms using C++ and compile it as a Python lib. However it's poorly documented. And as doc described, C API should be a basic option. Boost is built on C API any way.

Sample: I made it several years ago on a class. You can do: import tfidf.

Upvotes: 1

Ray
Ray

Reputation: 29

Add you python script or package's path to sys.path or just move them to one of the location in sys.path. BUT i do not suggest to do this...

Upvotes: -2

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