Initialization

This exercise provides a basic set of primitives to ensure constructors only run after other constructors they depend on had the chance to run.

In heterogeneous code bases, the "main" application has no obligation to know what initialization needs to be done and in what order.

In order to avoid having a centralized file littered with ifdefs containing the ordered calls for each handler, the primitives presented here exchange a bit of initial processing (very low overhead) to provide decentralized initialization.

So far the only "con" of this method is that all relevant projects must have this code as an extra dependency

Usage

Independent handlers

An independent handler has no dependency and will be one of the first to run

REGISTER_INDEPENDENT_CONSTRUCTOR(MyConstructor1);

Dependent handlers

A dependent handler will only run after its' dependencies run all the way.

REGISTER_DEPENDENT_CONSTRUCTOR(MyConstructor3, MyConstructor1, MyConstructor2);

Running all handlers

int main(void) {
    RunInitializationFunctions();

    // ... initialization complete, do whatever now ...

    return 0;
}

Concept

This exercise makes use of constructors that run without any specific order. Each constructor simply registers into a global structure the handlers and their dependencies.

A dependency is simply a handler that must run first. This function/address should be present in the header file, possibly hidden behind some macro

When a call to RunInitializationFunctions is performed, the handlers are organized and run in the appropriate order, taking their dependencies into account.

There are two assumptions made here:

1. The handlers belong to the same memory address space and therefore their values are unique. If this assumption cannot be maintained, then the initialization responsibility shifs either into a network protocol, or some operating system primitive

2. A handler has access to the address of the handlers it depends on. Often this is achieved by using the respective header file

RoadMap / Project Status

This exercises' main core is complete!

Valgrind shows no memory leaks if everything is properly shutdown!