我尝试过以下方法:
std::function<void ()> getAction(std::unique_ptr<MyClass> &&psomething){
//The caller given ownership of psomething
return [psomething](){
psomething->do_some_thing();
//psomething is expected to be released after this point
};
}
但它没有编译.有任何想法吗？
更新:
AS建议,需要一些新的语法来明确指定我们需要将所有权转移到lambda,我现在考虑以下语法:
std::function<void ()> getAction(std::unique_ptr<MyClass> psomething){
//The caller given ownership of psomething
return [auto psomething=move(psomething)](){
psomething->do_some_thing();
//psomething is expected to be released after this point
};
}
它会是一个好的候选人吗？
更新1:
我将展示我的实施move和copy如下:
template<typename T>
T copy(const T &t) {
return t;
}
//process lvalue references
template<typename T>
T move(T &t) {
return …我想将一个rvalue传递std::bind给一个在C++ 0x中采用rvalue引用的函数.我无法弄清楚该怎么做.例如:
#include <utility>
#include <functional>
template<class Type>
void foo(Type &&value)
{
Type new_object = std::forward<Type>(value); // move-construct if possible
}
class Movable
{
public:
Movable(Movable &&) = default;
Movable &operator=(Movable &&) = default;
};
int main()
{
auto f = std::bind(foo<Movable>, Movable());
f(); // error, but want the same effect as foo(Movable())
}
我正在尝试使用boost :: asio并遇到一些泥潭.
我正在尝试编译以下代码:
std::unique_ptr<buffer_t> buffer = buffers.pop();
std::function<void(const boost::system::error_code&, size_t)> t = std::bind(&tcp_client::handle_read_done,
this,
std::placeholders::_1,
std::placeholders::_2,
std::move(buffer));
如果我排除std :: move(缓冲区),当然从handle_read_done的签名和std :: bind中的传递参数,一切正常.
当试图将它传递给boost :: asio :: async_read_some时,它抱怨从std :: bind返回的对象上隐式删除的函数,对元组上的已删除函数,我假设是因为可移动性,以及大量的提升具体错误.如果我只是尝试将它分配到一个std :: function,它应该与提升调用的签名匹配,我得到那些相同的元组错误,所以我猜它们是相同的.只需将std :: bind的结果赋值给auto就不会产生编译错误,但当然我不能在其上调用任何东西.
我究竟做错了什么？以下是尝试分配时的输出std::function<void(const boost::system::error_code&,size_t)>
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional: In static member function ‘static void std::_Function_handler<void(_ArgTypes ...), _Functor>::_M_invoke(const std::_Any_data&, _ArgTypes ...) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _ArgTypes = {const boost::system::error_code&, long unsigned int}]’:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:2148:6: instantiated from ‘std::function<_Res(_ArgTypes …