Real-World Examples of Metaprogramming I

Advanced metaprogramming can appear very academic, so to demonstrate its usefulness, let’s look at some examples that demonstrate the syntax of metaprogramming and how it can be used in practice.

Example 1: creating a generic safe cast function

When casting between data types in C++, there is a multitude of different ways things can go wrong:

• We might lose a value if casting to an integer type of a lower bit length.

• We might lose a value if casting a negative value to an unsigned integer.

• The correct address might become incorrect if casting from a pointer to any integer than uintptr_t. This is because C++ only guarantees that uintptr_t is the only integer type to withhold an address.

• If casting from double to float, the result might be int if the double value is too large for ...