问题描述
我有一个类，该类在构造函数中将引脚的列表作为参数。
现在，此列表只是一个const数组（ const unsigned int（&spins）[N] ）。
我想以可以使用initializer_list和（const）数组的方式重载构造函数。
我可以使它与单独的类一起工作，但是我m无法将它们组合在一起。
I have a class that takes a "list" of pins as argument in the constructor.Right now, this "list" is just a const array (const unsigned int (&pins)[N]).I'd like to overload the constructor in such a way that you can use an initializer_list as well as a (const) array.
I can get it working with separate classes, but I'm unable to combine them.
我的测试班的基本结构：
The basic structure of my test class:
#include <iostream>
#include <cstring>
using namespace std;
class X
{
public:
X(... pins);
~X();
void print() {
for (unsigned int i = 0; i < length; i++)
cout << pins[i] << ' ';
}
private:
(const) unsigned int *pins;
const size_t length;
};
A类（使用std :: initializer_list）
Class A (using std::initializer_list)
public:
A(initializer_list<unsigned int> pins)
: length(pins.size()) {
this->pins = (unsigned int *)malloc(sizeof(unsigned int) * pins.size());
memcpy(this->pins, pins.begin(), sizeof(unsigned int) * pins.size());
}
~A() {
free(pins);
}
private:
unsigned int *pins;
B类（使用数组）
public:
template <size_t N>
B(unsigned int (&pins)[N])
: length(N) {
this->pins = pins;
}
private:
unsigned int *pins;
C类（使用const数组）
Class C (using a const array)
public:
template <size_t N>
C(const unsigned int (&pins)[N])
: length(N) {
this->pins = pins;
}
private:
const unsigned int *pins;
这允许我执行以下操作：
This allows me to do things like:
A a({1, 2, 3});
unsigned int pb[] = {4, 5, 6};
B b(pb);
const unsigned int pc[] = {7, 8, 9};
C c(pc);
a.print();
b.print();
c.print();
这会打印 1 2 3 4 5 6 7 8 9 如预期。
如何将这些不同的构造函数组合到一个类中？
我希望能够以上面显示的三种方式之一初始化对象。
How can I combine these different constructors in one class?I want to be able to initialize an object in either of the three ways shown above.
如果我做成 pins 一个 const ，我不能做 memcpy（pins，...）之类的事情，并且如果我不将其设为 const ，则不能使用const数组作为构造函数的参数。
If I make pins a const, I can't do things like memcpy(pins, ...), and if I don't make it a const, I can't use a const array as argument for the constructor.
（目标平台是Arduino，因此不支持大多数花哨且占用大量内存的C ++ 11技巧。）
(The target platform is Arduino, so most fancy and memory-intensive C++11 tricks are not supported.)
推荐答案
遵循以下思路：
class X
{
public:
X(std::initializer_list<unsigned int> aPins)
: storage(aPins), length(aPins.size()) {
pins = length ? &storage[0] : nullptr;
}
template <size_t N>
X(unsigned int (&aPins)[N])
: length(N) {
pins = aPins;
}
template <size_t N>
X(const unsigned int (&aPins)[N])
: length(N) {
pins = aPins;
}
void print() {
for (unsigned int i = 0; i < length; i++)
std::cout << pins[i] << ' ';
}
private:
const unsigned int* pins;
const size_t length;
std::vector<unsigned int> storage;
};
这篇关于具有const数组和initializer_list的C ++重载构造函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！