variadic

问题 Consider this working code: #include <iostream> #include <utility> #include <array> template <typename... Args> void foo (Args&&... args) { const auto v = {args...}; for (auto x : v) std::cout << x << ' '; std::cout << '\n'; } template <typename> struct Foo; template <std::size_t... Is> struct Foo<std::index_sequence<Is...>> { template <typename Container> static void execute (const Container& v) { foo(v[Is]...); } }; template <std::size_t N> void fooArray (const std::array<int, N>& a) { Foo

问题 My apologies if this has been asked before - searched with no definite answer, and I'm beginning to wonder if it is even possible. I am trying to learn C++11 and have run into trouble with variadic templates. I think I grasp (finally) the concept of variadic function parameters, and why/how recursion is used to unwrap and process them, but am having trouble with a (I think) similar concept in class constructors. Suppose I want to create a variadic template class that has a mixed-type

问题 I'm implementing some data structures, each supporting a set of commands such as INSERT value . I've used a tokenizer to generate a vector that holds each word/value. I want to be able to output to a .txt file the time every function call took, plus what the function returned if it does return something. For example, if the command is INSERT AVLTREE 4 , I want to just output the time calling avl.insert(4) took. If the command is SEARCH AVLTREE 4 , I want to output the time calling avl.search

问题 I have a class that gets initialized with a previously unknown number of arguments and I want it to be done on cli using python click package. My issue is that I can't manage to initialize it and run a click command: $ python mycode.py arg1 arg2 ... argN click_command because with variadic arguments option nargs=-1 click don't recognize the click_command as a command. How can I input N args and then run a command using click? Setting a defined number of arguments, like nargs=5 , solves the

问题 How can i make a class method with variable length parameters, in Objective-C? For example, a method like -arrayWithObjects: NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil]; 回答1: What you need is a variadic function. These functions take a flexible number of arguments, like NSLog , [NSArray arrayWithObjects:...] , etc. See this tutorial: http://www.numbergrinder.com/node/35 Copied from my answer here: Obj-C, trying to write an alternative to NSLog, but I want my function to

问题 I got a plain variadic template declaration, just like the classic one: template <typename... Arguments> class VariadicTemplate; What I need to achieve is in by letting the VariadicTemplate class do perform some type checking; the variadic template should check in some iterative form that all the arguments received should be let say of the type <Foo> . I have seen something similar somewhere but now I can not recognize where it was :P 回答1: struct Foo {}; #include <type_traits> template<class

问题 I am a little confused if it possible an how to use a variadic tuple as an argument in a function and how to initialize it. template <typename T, Arg ...> void foo (int a, std::tuple<T, sizeof(Arg)> TupleTest); ... foo(TupleTest(2, "TEST", 5.5)); How could that be implemented using c++0x? 回答1: You don't need to get the number of template arguments. Just do this: template <typename... T> void foo(int a, std::tuple<T...> TupleTest); // make_tuple so we don't need to enter all the type names foo

问题 I want to fill the template parameters passed to a variadic template into an array with fixed length. For that purpose I wrote the following helper function templates template<typename ForwardIterator, typename T> void fill(ForwardIterator i) { } template<typename ForwardIterator, typename T, T head, T... tail> void fill(ForwardIterator i) { *i = head; fill<ForwardIterator, T, tail...>(++i); } the following class template template<typename T, T... args> struct params_to_array; template

问题 High Guys, I have to define a polymorphic datatype for a tree that can have multiple nodes. Each node can have any number of children and a vlaue. This type will always have at least one node. I am new in Haskell so am asking how can i declare the node to have variable number of arguments. This is what i have now. This is a tree that can have a Node or a node with value (a) and two tree children. Instead of two tree children, i want them to be any number of tree children. (Analoog as java

问题 The PHP function array_map(...) expects a callback as first parameter (or null for creating an array of arrays) and a variable number of array arguments, e.g.: $foo => array_map(null, $bar, $buz); Now I have a case, where I need to pass to array_map(...) a variable number of arrays. I cannot hard-code this, since the arrays for the array_map(...) 's input are generated dynamically. function performSomeLogicAndGetArgumentsForMyFunction() { ... return ['bar' => [...], 'buz' => [...]]; } $foo =