CppCon 2015

Part I: Introduction to template metaprogramming. Template metaprogramming is a variant of generic programming, a technique that uses C++ template mechanism to perform computations at compilation time, usually to generate, from a single description, executable code that depends on the properties of the data types. It can be viewed as “programming with types”. In this example-driven class we start with the overview of the metaprogramming tools (everything you wanted to know about template specializations but were afraid to ask). We will apply these tools to simple examples, such as: how to sort a sequence in order of increasing values, unless it’s a sequence of pointers, in which case we want the values of what they point to. Part II: Advanced techniques and practical applications. Simple examples of metaprogramming are fun and useful, but once you master them you start chafing at the limitations. This is C++, where we don’t suffer limitations gladly. We therefore move on to the more advanced techniques, including SFINAE, and the appropriately more advanced examples. The journey takes us back to the beginning: after all, when sorting a sequence of values vs a sequence of pointers, you don’t really care whether the pointer is smart or dumb. What you really want to know is whether “*p” compiles or not. What you really need is an “if_compiles” metaprogramming function.