Expert Python Programming - Third Edition

Passing Python functions as C callbacks

It is a very popular design pattern to delegate part of the work of function implementation to custom callbacks provided by the user. The most-known function from the C standard library that accepts such callbacks is a qsort() function that provides a generic implementation of the quicksort algorithm. It is rather unlikely that you would like to use this algorithm instead of the default TimSort implemented in CPython interpreter that is more suited for sorting Python collections. Anyway, qsort() seems to be a canonical example of an efficient sorting algorithm and a C API that uses the callback mechanism that is found in many programming books. This is why we will try to use it as an example of passing ...