std::tuple<foo,bar,baz> buzz;
std::tuple<moo,meow,arf> bark;

auto my_cat_tuple = std::tuple_cat(buzz,std::move(bark));  // copy elements of buzz,// move elements of bark

如果元组的元素类型是可移动的或可复制的,上述将会起作用.除非你做这样的事情,否则它们不需要默认构造

decltype(std::tuple_cat(buzz,bark)) my_uncatted_yet_tuple;  // This will attempt to default construct the tuple elements

my_uncatted_yet_tuple = std::tuple_cat(buzz,std::move(bark));