我想知道我是否在以下使用了好的方法:
- 我想构造一个父类(A类),这个类应该拥有给定“Foo”类的一个实例
- 我希望父类拥有一个子类成员(B 类),并且该成员应该具有对父类的 foo 成员的引用。
下面的代码似乎有效,但我想知道我是否只是“幸运”编译器足够同情。
为了清楚起见,我在下面的评论中添加了评论和我的问题。
谢谢 !
struct Foo
{
std::string mValue;
};
class B
{
public:
B(const Foo & foo) : mFoo_External(foo) {}
private:
const Foo & mFoo_External; //this is an external reference to the member
//(coming from A)
};
class A
{
public:
//Here is the big question
//Shall I use :
// A(const Foo & foo) : mFoo(foo), mB(mFoo) {}
// or the declaration below
A(const Foo & foo) : mFoo(foo), mB(foo) {}
private:
//According to my understanding, the declaration
//order here *will* be important
//(and I feel this is ugly)
const Foo mFoo;
B mB;
};
void MyTest()
{
std::auto_ptr<Foo> foo(new Foo());
foo->mValue = "Hello";
A a( *foo);
foo.release();
//At this point (after foo.release()), "a" is still OK
//(i.e A.mB.mFooExternal is not broken, although foo is now invalid)
//
//This is under Visual Studio 2005 :
//was I lucky ? Or is it correct C++ ?
}