use anonymous namespaces for private free-standing functions.
do not inline stuff in the class definition.在class定义之外的头文件中另外写,不过我看C++的作者书上也没有这么要求过。
inline int Foo::value() const { return value_; }
in C++ you do not need to explicitly return from main.
npm config set registry=http://registry.npmjs.org
npm config set proxy=http://127.0.0.1:8087