Use this tag for questions about the C++ standard library template std::tuple. It represents an ordered, heterogeneous sequence of objects. Also add the tag [c++] when using this tag.
Questions tagged [stdtuple]
403 questions
2
votes
1 answer
error use of deleted function when trying to pass rvalue to a tuple
Original context:
I am trying to pass a tuple of (object, expected_value_of_some_property) to a test function
I created a simple class to reproduce the error I am facing:
template
class Vector
{
private:
size_t m_size;
…
Zaki
- 107
- 9
2
votes
2 answers
Inherit CTAD constructor
I have derived from std::tuple and but was unable construct the derived class from an initializer list due to issues with class template argument deduction. Is there a better way to construct such a class beyond just giving it an already constructed…
Tom Huntington
- 2,260
- 10
- 20
2
votes
3 answers
From boiler plate code to template implementation
I am implementing a finite state machine where all possible states are stored within a std::tuple.
This is a minimum compiling example of the problem I am facing and its godbolt link https://godbolt.org/z/7ToKc3T3W:
#include
#include…
Pablo
- 557
- 3
- 16
2
votes
1 answer
Support for std::tuple in swig?
When calling a swig generated function returning std::tuple, i get a swig object of that std::tuple.
Is there a way to use type-maps or something else to extract the values? I have tried changing the code to std::vector for a small portion of the…
Simon_lb
- 23
- 4
2
votes
3 answers
Printing Pairs inside tuple in C++
I am trying to print all the values of pair inside of a tuple,
header file
template
void printPairs(std::tuple t)
{
for (int i = 0; i <= 4; i++) //the value of 'i' is not usable in a constant expression
{
…
n9p4
- 304
- 8
- 34
2
votes
4 answers
c++ get std::vector from std::vector>
i want to initialize a const std::vector member variable in the initializer list of a constructor, given a std::vector> constructor argument. The vector should contain all the first tuple items.
Is there a one-liner that…
matthias_buehlmann
- 4,641
- 6
- 34
- 76
2
votes
1 answer
How to convert tuple into initializer list
I make large tuple with std::make_tuple function.
something like this
template
QCborArray array(const T&... args) {
return {args...};
}
but with tuple instead of parameter pack
LightSith
- 795
- 12
- 27
2
votes
1 answer
Return std::tuple containing const-reference in C++11
I have something like this (C++11)
std::tuple func()
{
return std::make_tuple(some_internal_reference, true);
}
the problem is that in the caller I cannot declare:
const MyType& obj; // this does not compile of course
bool…
Taw
- 479
- 3
- 15
2
votes
0 answers
Copy elision with tuples
I always had the wrong impression that if I create temporaries in a function that returns a tuple, and use std::forward_as_tuple in the return statement, then there is no copy, just like automatic copy elision for non-tuple return types.
How then…
fheshwfq
- 303
- 3
- 11
2
votes
0 answers
no matching function for call to std::get with const tuple ref as argument
I've been trying to make a generic function in order to build a query in SQL.
In order to do that, I went and used tuple with variadic template, in order to make the query more generic.
This is the code (This is not a final code so understand some…
Guy Ti
- 21
- 2
2
votes
1 answer
Forward the same argument to variadic tuple constructor in C++
TL;DR below
I am trying to write some C++ code using a package for multicore processing. The package has a nice sender class that I use to send messages between the threads. It looks something like this:
// structs provided by the package
struct…
student91
- 213
- 1
- 10
2
votes
2 answers
Extract types from std::tuple for a method signature
I am looking for a way to extract the types of an std::tuple to define a method signature. Take the following (contrived) example:
template
class A
{
public:
typedef RetT ReturnType;
typedef…
Alemarius Nexus
- 340
- 3
- 12
2
votes
3 answers
enable_if-like SFINAE expression for std::apply
I would like the ability to disable a function if a callable template argument is not callable via std::apply.
Perhaps it would help to explain the problem starting with what works. I have this for the regular function call case:
template
dsharlet
- 1,036
- 1
- 8
- 15
2
votes
1 answer
Split an std::tuple on an arbitrary index
I have an std::tuple and I want to split it at an arbitrary compile-time parameter N. I have seen solutions floating around for getting the head and the tail of an std::tuple like here , here or here , but these cannot solve my problem since for me…
dkoutsou
- 87
- 5
2
votes
0 answers
Why is constexpr with std::forward_as_tuple not working?
Why is the following not compiling? This is somehow counter-intuitive (not to say constexpr concepts are confusing):
#include
int main() {
constexpr const int a = 0;
static_assert(a == 0, "Wups");
constexpr auto t2 =…
Gabriel
- 8,990
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