I’m working on a project that is all in C because of its long history and legacy. We’re slowly modernizing the codebase and writing all our new code in Python (using NumPy, C extensions, and so on for performance where necessary). Occasionally, I just want to bang my head against the wall because there are things we can do so simply in any modern language that you just can’t do in any straightforward way in C. For example, I have file writers that all work exactly the same way, with the single exception that the format string and the data that you put into it vary for each file.

In Python, this would be straightforward to handle with the class machinery: you could simply specify the format string in each inheriting class and define the data points to be supplied at the top of an overriding function, call the parent function with super() and be done.

To do something similar in pure C is nearly impossible. You can supply a format string with each function (or module, or however you separate out the code), and if you feel especially clever you could convert all your data types to strings and pass them as a list to be printed by the standard function. The net result would be longer and less maintainable than simply having a set of essentially-duplicate functions, though.