在 C++ 中是否有通过引用返回新对象实例的正确方法？

所以我正在编写一些代码，我有这样的代码：

class Box
{
    private:
    float x, y, w, h;

    public:
    //...
    Rectangle & GetRect( void ) const
    {
        return Rectangle( x, y, w, h );
    }
};

然后在一些代码中：

Rectangle rect = theBox.GetRect();

Which worked in my debug build, but in release there were "issues" returning that Rectangle by reference -- I basically got an uninitialized rectangle. The Rectangle class has an = operator and a copy constructor. Without getting into why this broke, I'm actually more interested in the correct way to return a (new) object by reference for the purpose of assigning copying to a variable. Am I just being silly? Should it not be done? I know I can return a pointer and then dereference on assignment, but I'd rather not. Some part of me feels like returning by value would result in redundant copying of the object -- does the compiler figure that out and optimize it?

这似乎是一个微不足道的问题。经过多年的 C++ 编码，我不知道这一点，我感到几乎尴尬，所以希望有人能为我解决这个问题。 :)

您无法返回对堆栈上临时对象的引用。您有三个选择：

1. 按值返回
2. 通过指针通过引用返回到您使用 new 运算符在堆上创建的内容。
3. 通过引用返回您通过引用收到的参数。 [编辑：感谢@harshath.jr 指出了这一点]

请注意，当您按值返回（如下面的代码所示）时，编译器应优化分配以避免复制 - 即，它将通过将 create+assign+copy 优化为 create 来创建单个矩形（矩形）。仅当您从函数返回时创建新对象时，这才有效。

Rectangle GetRect( void ) const
{
    return Rectangle( x, y, w, h );
}

Rectangle rect = theBox.GetRect();