Intel Threading Building Blocks

Generic Programming

Bjarne Stroustrup, creator of C++, once considered there to be three fundamental styles supported by C++—procedural programming, data abstraction, and object-oriented programming—but later said that generic programming has become a fourth style.

We can give credit to the Standard Template Library (STL), created by Alexander Stepanov, for popularizing this style. It fits very well with the principles of C++, which favors abstraction and efficiency together.

In STL and Threading Building Blocks, algorithms are separated from containers. This means that an algorithm takes a recursive range and uses it to access elements within the container. The specific type of the container itself is unknown to the algorithm. This clear separation of containers and algorithms is the basic idea of generic programming. Separation of algorithms from containers means that template instantiations result in relatively little added code and generally only that which is actually going to be used.

Threading Building Blocks does embrace the same principles as STL, but does it through the use of recursive ranges, not iterators. Iterators in STL (except for random access iterators) are fundamentally sequential, and thus inappropriate for expressing parallelism. Random access iterators can, of course, express parallelism, and blocked_range is carefully defined so that blocked_range works for ranges defined by [begin,end) iterator pairs. In fact, an early design of Threading Building Blocks used ...