Functional style in C++: Closures, late binding, and lambda abstractions

C++ permits definition of a local class, within a function, method or block rather than in the global space. This feature makes nested functions and closures possible. Returning an object as the result of a function inevitably involves deep-copying of the object to and from temporaries, which may be expensive for big objects. Lazy construction, a late binding, is a simple and a very useful alternative. In this method, matrices themselves are never returned from functions; a function may however yield a recipe for how to make an object. In a code snippet, the first argument is the title of a test case and the second argument is a test's body itself, specified as an anonymous function, a genuine abstraction.