运算符new如何调用类的构造函数? [英] How operator new calls the constructor of class?

问题描述

我知道，new运算符将调用类的构造函数.

I know that, new operator will call the constructor of class.

但是它是如何发生的，用于此的底层技术是什么.

But how it's happening, what is ground level techniques used for this.

推荐答案

这是我的想象:

T* the_new_operator(args)
{
    void* memory = operator new(sizeof(T));
    T* object;
    try
    {
        object = new(memory) T(args);   // (*)
    }
    catch (...)
    {
        operator delete(memory);
        throw;
    }
    return object;
}

(*)从技术上讲，它并不是真正在调用新的位置，但是只要您不超载，心理模型就可以正常工作:)

(*) Technically, it's not really calling placement-new, but as long as you don't overload that, the mental model works fine :)

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