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Older articles (2/16)

  1. Database scheme for resin recipes

    This document explores how an SQLite database could be used to store data for the resin-calculator. Normally, the recipes are a dictionary keyed to the name of the resin. The value of each recipe is a list of (component, parts-by-weight) tuples. Since a database only contains tables, where each row has the same form, how do we store such infomation in a database?

  2. Convert RCS history to git

    Before the rise of git, I used rcs as my version control system. Because I want to standardize on git, I am slowly converting old repositories.

    In this article I’ll be converting my old perl scripts in ~/src/perl.

  3. Doing calculations with Python

    As an engineer I do a lot of calculations. These can be done with pen and paper and a calculator, in an IPython notebook or in a throwaway spreadsheet. All of these methods have shortcomings, though.

    Pen and paper is hard to share and (in my case) hard for others to read. In IPython you can assign the results of calculations to a variable, but you have to perform a separate action to display them. And spreadsheets in general show you the results but not the calculations.

    So I wrote a simple function in Python to help me with that. Using this function I can print both simple assignments and relatively complex calculations. And it shows both the calculation and the result.

  4. Structures in Python

    Sometimes I miss the C’s plain old struct in Python.

    Of course Python has dictionaries, but I prefer to write a.b over a['b'].

    Here are several ways of doing something akin to a struct in Python.

  5. Building gphoto2-ffi on FreeBSD

    Download

    Clone the repository from https://github.com/jbaiter/gphoto2-cffi.

    > cd ~/github
    > git clone https://github.com/jbaiter/gphoto2-cffi
    

    Build

    I had to specify where to find the include files.

    > env C_INCLUDE_PATH=/usr/local/include python3 setup.py build
    

    Install and clean-up

    # python3 setup.py install
    # python3 setup.py clean …

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