Tag: Python

The ultimate guide to Python decorators

Decorators are one of the most beautiful feature of Python programming language. They can make code easy-readable and maintainable. Nevertheless, their usage may seem tricky and mysterious in the beginning. This is a guide to the world of decorators. I hope that you will feel like a pro and have no questions left about them after exploring this article.

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A micro Lisp interpreter experiment

While reading the Binary trees chapter from Programming Interviews Exposed by John Mongan et al. I started thinking of alternative recursion examples which do not involve sorting, generating Fibonacci sequence, binary tree traversal and similar tasks. Lisp! Lisp is inseparable from recursion and Lisp interpreter would be a good case to demonstrate what recursion is and how it can be used efficiently. What would be a minimal simplified Lisp interpreter written in Python? Surprisingly, I managed to do it just in 6 lines of Python code! And this is not just because of Python being a wonderful language, but because of Lisp being such a beautiful and simple concept.

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PyRegs: The Python Regex Debugger

Long ago, I learned the regular expressions in order to write a simple syntax highlighting engine. Regular expressions are not hard to master, but take time to practice. Kodos was the regex debugger of my choice, as it was written in Python. All these years Kodos was a "must have" tool on my development machines. Suddenly with the new version of Debian operating system, Kodos was not in the repositories anymore! Why? Kodos is based on QT3 widgets toolkit, which is a bit outdated nowadays (QT5 has been released recently) and was removed from Debian 7.0 ("Wheezy"). That is how I decided to write a small Python regex debugger in Python 3 and its de-facto standard Tkinter bindings to the Tk GUI toolkit.

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Kaylee

I just returned from my summer vacation and can finally state: another summer is over. But wonderful summer it was! I finally graduated and got a Master's degree in computer science. I cycled a lot and upgraded my MTB skills. I read lot of fiction. And somewhere between work, sports reading and sleeping was Kaylee, a distributed and volunteer in-browser computing framework.

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Inside Python: understanding os.listdir()

If you've been using python for a long time, then you surely know that os.listdir() function returns an unsorted list of file names. I didn't care much until facing a situation, in which the sorted-sequential processing of files was crucial, and I could not remember whether the previous file processing were done in sorted order. Well, luckily they were. But hey, this is a little bit annoying, isn't it? Why os.listdir() returns an unsorted list of files? Would you like to find out?

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Inside Python subprocess communication

Sometimes, it's really hard to understand what happens inside a function or even a whole module of Python's Standard library. For example, the subprocess module contains a very tricky Popep class. I tried to use the the module to communicate with a MATLAB subprocess shell (e.g. send MATLAB commands to subprocess and read the output). Unfortunately I failed and was just able to pass a MATLAB script via command-line arguments. Yet, I learnt much about the Popen.communicate() method and I'd like to share this knowledge with you.

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