没有子类的C对象？

我想知道是否有办法在c中声明一个对象以防止它被子类化.是否有相当于在 Java中声明最终对象？

解决方法

从 C++ FAQ,section on inheritance起

This is kNown as making the class
“final” or “a leaf.” There are three
ways to do it: an easy technical
approach,an even easier non-technical
approach,and a slightly trickier
technical approach.

The (easy) technical approach is to
make the class’s constructors private
and to use the 07001
to create the objects. No one can
create objects of a derived class
since the base class’s constructor
will be inaccessible. The “named
constructors” themselves Could 07002 or they Could 07003.

The (even easier) non-technical
approach is to put a big fat ugly
comment next to the class deFinition.
The comment Could say,for example,//
We'll fire you if you inherit from
this class or even just /*final*/
class Whatever {...};. Some
programmers balk at this because it is
enforced by people rather than by
technology,but don’t knock it on face
value: it is quite effective in
practice.

A slightly trickier technical approach
is to exploit 07004.
Since 07005,the following
guarantees that no concrete class can
inherit from class Fred:

class Fred;

 class FredBase {
 private:
   friend class Fred;
   FredBase() { }
 };

 class Fred : private virtual FredBase {
 public:
   ...
 };

Class Fred can access FredBase‘s ctor,
since Fred is a friend of FredBase,
but no class derived from Fred can
access FredBase’s ctor,and therefore
no one can create a concrete class
derived from Fred.

If you are in extremely
space-constrained environments (such
as an embedded system or a handheld
with limited memory,etc.),you should
be aware that the above technique
might add a word of memory to
sizeof(Fred). That’s because most compilers implement virtual inheritance by adding a pointer in objects of the derived class. This is compiler specific; your mileage may vary.

原文地址：https://www.jb51.cc/c/116854.html