lambda 表达式的可变参数模板
使用 g++ 的正确方法是什么:
What's the correct way to do this with g++:
template < typename F >
void g (F f);
template < typename ... A >
void h (A ... a);
template < typename ... A >
void f (A ... a) {
g ([&a] () { h (a...); }); // g++-4.6: error: parameter packs not expanded with ?...?
}
推荐答案
我想你也需要在捕获列表中展开pack a，像这样:
I think you need to expand the pack a in the capture list as well, like this:
template < typename ... A >
void f (A ... a) {
g ([&, a...] () { h (a...); });
}
这是来自 C++0x 最终委员会草案，第 5.1.2.23 节的相关文本:
Here is the relevant text from the C++0x Final Committee Draft, section 5.1.2.23:
捕获后跟省略号是包扩展(14.5.3).[ 例子:
A capture followed by an ellipsis is a pack expansion (14.5.3). [ Example:
template<class... Args> void f(Args... args) {
auto lm = [&, args...] { return g(args...); }; lm();
}
―结束示例]
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