问D编程:组件边界的接口

EN

#include<iostream>

class I // Our interface-by-convention
{
public:
    virtual void foo() = 0;

    void bar() // OK, non-virtual members do not affect binary compatibility
    {
        /* ... */
    }
};

class C : public I
{
private:
    int a;

public:
    C(int a) : a(a) {}

    void foo()
    {
        std::cout << a << std::endl;
    }
};

// This function will be used from the D side
I* createC(int a)
{
    return new C(a);
}

extern(C++) interface I
{
    void foo();

    final void bar() // OK, non-virtual members do not affect binary compatibility
    {
        /+ ... +/
    }
}

// Link `createC` from the C++ side
extern(C++) I createC(int a);

void main()
{
    I i = createC(2);
    i.foo(); // Write '2' to stdout
}