Hi folks,

In this post I talk about a good way to perform actions when your Python program completes. For example you may want to clean up temporary files created by program or close database connections or other resources resources when your program terminates. You may want to do this regardless of whether the program finishes successfully or crashes due to an error. An excellent way to perform such clean-up tasks automatically is to use the atexit module. Here is an example below of how to use it in a class below.

import atexit


class Foo:

    def __init__(self):
        atexit.register(self.goodbye)
        x = 5

    def goodbye(self):
        print('You are leaving the program')



f = Foo()

If you run the following code, you will see the message ‘You are leaving the program’ just before the program exits.

Here is another example where we intentionally cause the program to crash.

import atexit


class Bar:

    def __init__(self):
        atexit.register(self.goodbye)
        x = 5 / 0 # error!

    def goodbye(self):
        print('You are leaving the program')



f = Bar()

If you run this program, you will see the error, but nevertheless still see the message ‘You are leaving the program’ printed before the program exits.

You can read more about atexit in the Python documentation.

That’s it for now. Happy software development.

Hi folks,

Here is an easy way to run system commands in Python and get the output. It is by using subprocess.getoutput command. E.g.

import subprocess
output = subprocess.getoutput("ls -l ~")
print(output)

That’s all for now. Till next time, happy software development.

Hi folks,

If you have done a lot of debugging with ipdb on Python projects in a windows environment using tools like Git bash, you may notice that it’s not very easy to exit ipdb. Pressing familiar keys like Ctrl + c doesn’t work. Here’s how to exit ipdb in Windows:

Run the following command

import os; os._exit(0)

That’s all for now. Till next time.

Hi folks,

In this post I talk about how to pip install Python projects from source.

Let’s say you have a project that you can normally install via pip using a command like pip install someproject, but you want to make some customization to the project.

Here’s how to go about it.

• First, clone the project from Github.
• Make any modifications to the project source code as desired.
• Then change to the project’s root directory.
• Run the following command to install the project

pip install -e . 

• If you have the project’s library already installed and you upgrade that version to the latest from your source code using command

pip install -e . -U

That’s all for now. Happy software development.