Optimization of "Concrete Factories" (variations of the Pimpl idiom)

Pimple例子，通过一个小例子讲解C++中pimple惯用法的用法，领略其好处-Pimple example, through a small example to explain C++, pimple idiom usage and enjoy its benefits

实现类 接口和实现的分离 采用pimpl idiom方式-pimpl idiom

pimpl 手法在 C++ 里已是“高手”们广泛运用的成熟方法之一，它的优点很多，诸如降低编译依赖、提高重编译速度之类的工具性优势自不待赘言，而其对“保持接口稳定性”的优点更值得称道。-pimpl practices in C++ where is the " master" were widely used sophisticated methods, it has many advantages, such as reducing build dependencies an