Expression templates

Expression Templates is a C++ technique for passing expressions as function arguments. The expression can be inlined into the function body, which results in faster and more convenient code than C-style callback functions. This technique can also be used to evaluate vector and matrix expressions in a single pass without temporaries. In preliminary benchmark results, one compiler evaluates vector expressions at 95-99.5% efficiency of handcoded C using this technique (for long vectors). The speed is 2-15 times that of a conventional C++ vector class.