Templatemetaprogrammointia

Templatemetaprogrammointia, often referred to as template metaprogramming in English, is a programming technique that uses a programming language's template system to perform computations at compile time. This means that rather than executing code during the program's runtime, the computations are carried out by the compiler itself before the program is even run. This allows for the generation of highly optimized code, as many calculations and decisions can be pre-determined and baked directly into the executable.

The primary language that popularized this technique is C++. In C++, templates are a powerful feature that allow for generic programming, enabling code to operate on different data types without needing to be rewritten for each type. Template metaprogramming leverages this by treating template instantiations as a form of computation. The compiler, when processing template code, effectively executes a Turing-complete language. This can be used to perform complex calculations, generate lookup tables, perform type checking, and even create entire code structures based on compile-time conditions.

The benefits of template metaprogramming include significant performance improvements, as runtime overhead is eliminated. It can also lead to more robust code through compile-time error checking and validation. However, it comes with drawbacks. Template metaprogramming can make code significantly harder to read, write, and debug. Compile times can also increase substantially due to the extensive computations performed by the compiler. Despite these challenges, it remains a valuable tool for certain performance-critical applications and in the development of high-level libraries.