Semi-technical thoughts

Sorry, it's not a complete instruction, just a thought. It occurred to me (some time ago) that Python's virtualenv is, essentially, a simplified version of system "prefix", it has bin, lib, include, and can have more stuff when needed. If you're willing to experiment (you'll probably have to set a few additional environment variables and/or build flags but that's no big deal), you can install various other tools there up until you have a complete system with its own compiler and complete set of libraries although it's much simpler to keep using system compiler and libraries only complimenting them when needed. Granted, prefixes are nothing new, people were using /opt (and their home directory) this way since the beginning of time. But with little help of virtualenv-wrapper or pyenv you can easily switch between them and isolate environments better. Binaries and stuff installed in virtualenv would override system defaults but only when venv is activat...

There are quite a few ways you can format a multi-line function call/list/dictionary in a programming language. With Python (at least with PEP8) it's just two ways: hanging indentation and vertical indentation. The latter is quite straight-forward and I mention it in the notes below. The former one is what this post is about. Well, about a minor but important question of where to place the closing bracket when using it. Yes, style is much more than formatting the commas and brackets so let's settle this and move on to the more important questions. When using hanging indentation, the only true way is this one(*): some_tuple = ( # Nothing here, only opening bracket. item1, item2, item3, item4, # Several items on one line is acceptable though not recommended. item5, # Last comma is important. And never, never place the closing bracket here. ) # Again, nothing here but the bracket and it's on the same level as the opening line. Empty line after the o...

Many companies these days are starting using Docker in their workflow, both big shots and tiny startups, even open-source projects which might sometimes be somewhat conservative when it comes to tools. I'm not trying to provide any kind of instruction here but instead to ask questions you should be asking yourself before following or not following their lead. I'm concentrating on context of web services using Django and Python, but it should be applicable to more or less anything. I must admit that Docker is cool. Linux containers is a fascinating thing itself and Docker is a great tool for simplifying their use for whatever purpose. Reusable and simple to build and share images, an easy way to launch those images and do stuff with them is a must if you use them. But should you containerize everything? It might, on the other hand, over-complicate your process without any significant benefits. So the first question is: do you even need containers or would you better off withou...

Every developer knows  datetime.strftime()  method, but some don't know that its argument's format is not documented in full in the official documentation. For example, you won't find any mention of %s directive there which means UNIX epoch time, timestamp. It works (at least with every major version of Python on Linux, FreeBSD, and MacOS), I've tested it a few times myself, it's just not documented. I recently saw a piece of code where developers, being unaware of such a directive, used custom format string with both datetime.now() and time.time(), a function generator, and on top of it messed with model migrations (it all was about FileField.upload_to if you know what I'm talking about) when they could just use %s. From other undocumented features you might be interested in these: %C  is a century (%Y//100), could be helpful for complimenting %y or something, I guess. %u  is a weekday number with Monday as 1 and Sunday as 7 (as opposed to %w represen...

I usually use Vim for my coding and all other stuff requiring text editing. There are a lot of plugins, scripts, configs, packs for Vim and a lot of them help with Python. But  so far I could not find the pack I'd love and I'm too lazy to make it on my own, so I usually throw out and re-create my whole Vim config dir once a year or so. This time I used Klen's Python Mode  and it's good judging by number of tools involved: almost all code style/syntax helpers I know (pep8, pep257, pyflakes, pylint, mccabe, and pylama to integrate them), autopep8 to help with formatting and stuff, rope for refactoring (sorry, I won't overwhelm this post with links – look for them in readme in github repo). It can more or less integrate with virtualenv and, of course, use Python syntax and identation plugins for Vim. It provides commands for almost everything but doesn't provide a lot of convenient hot-keys. Also there are no hotkeys for Django stuff: I'd like to have hotke...