是否可以让一个类只在命名空间内可用？还是有另一种方式，不使用命名空间？ 我正在努力创建一个框架，但不希望该框架的用户可以访问所有类，而只能访问特定类。
但是:无论如何，用户应该能够访问所有定义以创建指向这些类的指针变量。此外，他不应该能够访问这些类的所有数据成员，但我希望我的框架能够访问所有数据成员。
这可能吗？
示例(只是对我的请求的解释):
/* T2DApp.h */
namespace T2D {
// I don't want the user to be able to create an instance of this class (only pointer vars), but the framework should be able to.
class T2DApp {
public:
// constructor, destructor... //
SDL_Window* Window;
SDL_Surface* Surface;
bool Running = false;
}
}
/* T2D.h */
#include "T2DApp.h"
void init();
/* T2D.cpp */
#include "T2D.h"
void init() {
T2D::T2DApp app; // function in framework is able to create new instance of T2DApp.
app.Window.Whatever(); // every data member should be available to framework directly without getter methods.
app.Window.Whatever(); // dito
app.Running = true; // dito
}
/* [cpp of user] */
#include "T2D.h"
void main(etc.) {
...
T2D::T2DApp app; // User shouldn't be able to create an instance of T2DApp
T2D::T2DApp* p_app; // but he should still be able to "see" the class definition for creating pointers
...
p_app.Running = true; // User shouldn't be able to access this data member
p_app.Window.Whatever(); // But he should be able to access the other data members
p_app.Surface.Whatever(); // dito
...
}
非常感谢您:)
最佳答案
可以用 Pimpl idiom :
"Pointer to implementation" or "pImpl" is a C++ programming technique that removes implementation details of a class from its object representation by placing them in a separate class, accessed through an opaque pointer.
关于C++:使类及其某些数据成员仅在 namespace 中可用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47042165/