c++ - 为什么 C++ 中没有基类？

Question

从设计的角度来看，为什么在 C++ 中没有万能的基类，而其他语言中的 object 通常是什么？

Answer 1

最终裁决见 Stroustrup's FAQs .简而言之，它不传达任何语义。这将是有代价的。模板对容器更有用。

Why doesn't C++ have a universal class Object?

• We don't need one: generic programming provides statically type safe alternatives in most cases. Other cases are handled using multiple inheritance.

• There is no useful universal class: a truly universal carries no semantics of its own.

• A "universal" class encourages sloppy thinking about types and interfaces and leads to excess run-time checking.

• Using a universal base class implies cost: Objects must be heap-allocated to be polymorphic; that implies memory and access cost. Heap objects don't naturally support copy semantics. Heap objects don't support simple scoped behavior (which complicates resource management). A universal base class encourages use of dynamic_cast and other run-time checking.