Basic Packaging

As mentioned we want to create a package out of this file:

number_magic.py

def addition(arg1, arg2):
    """
    This functions adds the first and the second argument.

    :param arg1: the first summand
    :type arg1:  float
    :param arg2: the second and last summand
    :type arg2:  float
    :return:     the sum of both summands
    :rtype:      float
    """
    return arg1 + arg2

Make it a package

Right now it is just a plain python file. To make it a package you need to folder and add a __init.py file, that can be empty. Now we created a python package that can be imported.

Try it. Open a terminal and do

cd /path/containing/folder
python

We will assume you called the folder above plain_magic. So try to import the package.

import plain_magic

If that does not throw any import error we have a python package now.

The directory should look like this now:

some_directory/
   plain_magic/
      __init__.py
      number_magic.py

Enable Installations

Check Package Import

Now we solve the problem that you cannot import your package everywhere. Try it by doing:

# now switch directories
cd /tmp
python

So try to import the package.

import plain_magic

It should complain and throw an ModuleNotFoundError.

So lets solve the problem

Create a setup.py

Now create a setup.py according to the instructions of the Kiwi template documentation.

How can you check if you succeded?

Try to install it and import the package from somewhere else.

So open a terminal

cd /parent/directory/of/plain_magic
pip install -e .

Now you go back to Check Package Import and try to import it from another directory.

The directory should look like this now:

some_directory/
   plain_magic/
      __init__.py
      number_magic.py
   setup.py

Write a Command Line Interface

Now we want to be able to use our package from the command line:

some-magic-cmd adding-two-numbers --first-summand 1 --second-summand 2

Therefore you need to create command line interace similar to the one in the template here. In particular you need to create a cli.py.

To check if you succeeded you need to

• reinstall your package

• call the command from the command line

For solutions take a look the template package

The directory should look like this now:

some_directory/
   plain_magic/
      __init__.py
      cli.py
      number_magic.py
   setup.py