This post is about generating a file reading/writting library from some sort of specifications, in this case in the form of an xml file that details the internal binary structure of the file. Using this approach, we can define the format in an xml file and create some code generating tools to write code for libraries which read and write in that format for a given language such as C++ or python. These tools will also create some models in the respective programming language that are read and populated by the generated library. This has the advantage in case the format changes we just run the tool again with the updated format from the xml file. The code for reading the format will be updated and all that we need to do is to recompile it. It also allows people who are not familiar with programming to edit the format without writing code. I am going to use an open source project called niflib which reads and write 3d models in files for games like Elder Scrolls Skyrim. You can find