C ++-使用decltype或auto创建一个临时对象 [英] C++ - Creating a temporary object with decltype or auto

问题描述

我有一个对象"a"，我想将其复制到对象"b"中，但对其进行一些修改而不修改"a".然后看起来像这样:

I have an object "a" and I want to copy it into an object "b" but modify it a bit without modifying "a". Then that would look like this:

class SomeClass{

public:
    int a;

public:
    SomeClass(int _a)       {a = _a;}
    SomeClass& doStuff()    {++a; return *this;}

};

const SomeClass a( 25);
const auto b = SomeClass( a).doStuff();

这很好用，但是可以说我现在/不想写"a"的类型，然后我想出了以下解决方案:

This works nice but lets say I don't now / don't want to write the type of "a", then I came up with this solution:

const auto b = std::remove_const<decltype( a)>::type( a).doStuff();

我这样做正确吗?是否有一个不太丑陋的解决方案?(在这里我不必两次键入"a".)使用auto或其他方法.最好不是宏.

Am I doing this right? Is there a less ugly solution for this? (where I don't have to type "a" twice.) Using auto or something. Preferably not a macro.

推荐答案

如何

template<typename T>
T copy(const T& t) { return T(t); }

const auto b = copy(a).doStuff();

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