Abstraction • Documentation • Efficiency • Expressivity • Detecting errors • Doing something (by accident) that does not “fit” the type will be detected as error. 24What are types used for in programming

b.actual_str); }  Unfortunately, it’s still possible to use std::swapwith Saks::strings by accident… 75 The std::swap Two-Step  For example, here’s another type Personwith a custom swapfunction

privates is wrong Data members should be private std::pair.first, std::pair.second => is a language accident… Why? Because it doesn’t properly allow different behaviors, e.g. a pair initialized with a single

DataHeapType* _theDataHeap = new (buf) DataHeapType; return _theDataHeap; } Or was it an accident?Why is faster than ? A′ A int main(int argc, char **argv) { topFrame = (voi

becomes a necessary design tool. (A beautiful example of this method is given in Chapter 9.) It is an accident of history that the work on operation decomposition preceded that on data representation. How unfor-