这个函数允许客户端请求对象提供关于自己的其它方面的指针，这个新指针同样指向不同的虚基类（也叫做接口）。
This function allows a client to ask the object for different pointers to itself that also point to different abstract base classes (also known as interfaces).
Widget(所有pygtk部件的基类)的一些foo方法在内部调用虚方法do_foo。
Several foo methods of gtk.Widget (the base class for all PyGTK widgets) internally call the virtual methods do_foo.
类包含或者继承一个或多个纯虚函数，这样的类就是抽象基类。
A class containing (or inheriting) one or more pure virtual functions is an abstract base class.
在基类中可以通过将虚函数声明为纯虚函数的手段来定义抽象类，强制派生类在自己的类定义中实现虚函数的具体功能。
In a base class, abstract class is defined by declaring pure virtual function, a derived class must define all inherited pure virtual functions of its base classes to be concrete.
当你通过基类的指针来调用虚函数，技术也是一样的。
When you invoke calls through a pointer to the base class, the technique is the same.
这有效地隐藏了基类中的虚函数。
This effectively hides the virtual function in the base class.
当抽象类从基类继承虚方法时，抽象类可以使用抽象方法重写该虚方法。
When an abstract class inherits a virtual method from a base class, the abstract class can override the virtual method with an abstract method.
如果函数用作静态成员函数，则重命名该函数，以便不与基类虚函数冲突。
If the function was intended to be a static member function, rename it so it doesn't conflict with the base class virtual function.
类函数定义与基类中的虚函数同名，但参数的数目或类型不同。
A class function definition has the same name as a virtual function in a base class but not the same number or type of arguments.
派生类继承虚拟基类的虚函数的多个重写。
The derived class inherits more than one override of a virtual function of a virtual base class.
子对象多重继承自多个基类，每个基类都有虚函数，那么子类对象的内存布局是什么样的？
A function that is virtual in a base class is implicitly virtual in its derived classes. When a derived class overrides a virtual, the parameters in the base and derived classes must match exactly.
当使用与基类虚函数相同的名称进行声明时，成员模板函数不能是虚函数并且不能从基类重写虚函数。
Member template functions cannot be virtual functions and cannot override virtual functions from a base class when they are declared with the same name as a base class virtual function.
当使用与基类虚函数相同的名称进行声明时，成员模板函数不能是虚函数并且不能从基类重写虚函数。
Member template functions cannot be virtual functions and cannot override virtual functions from a base class when they are declared with the same name as a base class virtual function.
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