Hi, I'm Tomasz

Why Observer is so cool? Managing complexity in large code base is all about decoupling. Observer is a perfect tool to do that. The Observed object has no idea about its observers, no dependency injection is required at all, as a result a loose coupling is achieved between two classes of objects where the only common part is the interface they agree upon. First iteration It’s a classic design pattern and I’m sure majority (if not all) of engineers know the details behind it, most of us implement it in a slightly different way, depending on the requiremenets and the code base we are working with though.

Why signals are important Signals are the simplest form of IPC in Unix like systems. They are notifiers to the process that an external event has happened. As this is a system specific mechanism, there’s no portable C++ STL library providing support for signal handling. But it’s fairly easy to write one. First though a short introduction is required. Signal disposition Each thread in a process has a signal mask which can be modified either via setprocmask (for single threaded processes) or pthread_sigmask (for multithreaded processes).

Callbacks are a perfect way for clients to interface with an API abstracting an events source. How to design an API for such abstraction to make it unambiguous and easy to use? The simplest choice is functor injection, similarly as it is done on many instances in STL (or even C stdlib by means of function pointers). Can we do better though and what are the alternatives available? In this post I’ll try to provide a step by step overview of a design process for an imaginary HttpServer class.