如何在visual C ++ 2013中嵌套initializer_lists [英] How to do nested initializer_lists in visual C++ 2013
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问题描述
我有一个工作在g ++和clang,使用嵌套的initializer_list的程序。在Visual C ++中,1D情况下工作,但2D嵌套initializer_list不。有没有使Visual C ++工作的窍门,或者这是一个在他们的实现中的错误?
I've got a program which works in g++ and clang, using a nested initializer_list. In Visual C++, the 1D case works, but a 2D nested initializer_list does not. Is there a trick to make Visual C++ work, or is this maybe a bug in their implementation?
这是我的示例代码。如果我删除注释的行,它在Visual C ++ 2013。
Here's my example code. It works in Visual C++ 2013 if I remove the annotated line.
#include <iostream>
#include <initializer_list>
using namespace std;
template<class T>
void print(T val) {
cout << val;
}
template<class T>
void print(initializer_list<T> lst) {
bool first = true;
cout << "[";
for (auto i : lst) {
if (!first) cout << ", ";
print(i);
first = false;
}
cout << "]";
}
template<class T>
void print(initializer_list<initializer_list<T>> lst) {
bool first = true;
cout << "[";
for (auto i : lst) {
if (!first) cout << ", ";
print(i);
first = false;
}
cout << "]";
}
int main()
{
print({1, 2, 3});
cout << endl;
// Without this line, Visual C++ 2013 is happy
print({{1, 2}, {3, 4, 5}, {6}});
}
推荐答案
template<class T>
std::initializer_list<T> list( std::initializer_list<T>&& l ) { return std::move(l); }
或类似的东西至少可以为您提供解决方法:
or something similar may at least give you the workaround:
print( { list({1,2}), list({3,2,1}) } );
语法可以乱七八糟( l * {2,1}
)。
the syntax can be messed around with (l*{2,1}
) in a few ways as well.
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