In software development practice, the task of dynamically modifying program code is often faced depending on current or configured parameter values. Callbacks are widely used to solve this problem. C++ implements callbacks in a variety of ways, and it is not always obvious which is the best for a particular situation. The book examines the theoretical and practical aspects of organizing callbacks, analyzes the advantages and disadvantages of various implementations, and develops recommendations for selection depending on the requirements for the software being designed. First of all, the book is intended for intermediate level programmers, i.e. those who already know the C++ language quite well, but would like to expand and deepen their knowledge in the field of design and design. To a certain extent, it will also be of interest to experienced developers, on the one hand, as a systematization of knowledge, on the other hand, as a source of ideas and methods for solving practical problems.