Questions tagged [parameter-pack]
171 questions
1
vote
1 answer
May I implement this function with a parameter pack?
template typename ... tys_str
↑ I cant define the parameter pack
to express that paramater pack is constrainted to basic_string classes with a template argument */ >
void
concat_strings(…
Boma Kim
- 33
- 5
1
vote
0 answers
Parameter pack within template class constructor throws unexpected end-of-file found (C1004)
I have a template function that works okay by itself:
// some_util_file.h
namespace ArgsUtil
{
struct Args
{
void* item;
Args* next{ nullptr };
};
template
static void…
Froppy
- 11
- 2
1
vote
0 answers
Add members at compile time without copy/move constructors
I'm learning about Variadic Template and Fold Expression.
I would like to avoid the use of dynamic allocation and pointers.
To illustrate my problem, I created the Foo (copy and move constructors are deleted) class which inherits from I_Foo.
class…
Guillaume BERLAND
- 41
- 5
1
vote
2 answers
Generate a sequence of null values follwed by one at compiletime
I have a problem similar to
Generating a sequence of zeros at compile time
However, in my case I have no pack to expand. The situation is like this:
template
void foo()
{ bar(T{}, ..., static_cast(1)); }
There are N - 1 T{}:s followed…
user877329
- 6,717
- 8
- 46
- 88
1
vote
1 answer
How to defer expanding a parameter pack?
I was toying around with tuples. I wanted to zip an arbitrary number of tuples. There is probably a better way to do that than what I came up with, but my solution led me to a problem that is interesting in itself.
Sometimes, you want to expand one…
okovko
- 1,851
- 14
- 27
1
vote
1 answer
Is there a way for a class template to deduce the size of a parameter pack passed to the constructor?
If I have a class template like such:
template
struct foo
{
template... Ts>
foo(Ts... ts);
}
Is there any way whatsoever to deduce the template parameter N from the size of the parameter pack passed to…
JensB
- 839
- 4
- 19
1
vote
3 answers
Create string according to the parameter pack arguments count
I have a function with a parameter pack, I pass this pack to the fmt::format function, and I want to create a formatStr according to the args count, meaning add "{}#" for each passed argument.
I can do it using iterating, but is it possible to do…
Hardwired
- 804
- 1
- 8
- 19
1
vote
5 answers
Slice parameter pack parameters
I would like to split a parameter pack in all the first and one last parameter, but C++ requires the parameter pack be the last in the function declaration, so this is not valid code.
template
void func( Ts... args,…
Generic Name
- 1,083
- 1
- 12
- 19
1
vote
1 answer
Why does the compiler issue a template recursion error?
I'm currently trying to deduce a std::tuple type from several std::vectors that are passed as parameters. My code works fine using gcc, but the compilation fails with Visual Studio Professional 2019 with the message "fatal error C1202: recursive…
user16372530
- 692
- 2
- 13
1
vote
0 answers
C++ "fatal error C1202: recursive type or function dependency context too complex" in visual studio, but gcc compiles
Edit2:
I rephrased the question and asked specifically, where the template recursion occurs in this question: Why does the compiler issue a template recursion error?.
There, it turned out that problem is actually not related to my code, but…
user16372530
- 692
- 2
- 13
1
vote
1 answer
Nested initializer lists
I am making an attempt in creating dynamic Python-like dicts in C++.
One possible approach to implementation (which has its drawbacks, for sure) is
#include
#include
#include
Mike Land
- 436
- 4
- 15
1
vote
0 answers
Check template parameter pack for specific values
I am writing a small Tensor class, that should look like this:
using namespace std; // for simplicity
template
class Tensor {
size_t rank_;
array size_;
vector data;
public:
template
Urwald
- 343
- 1
- 10
1
vote
2 answers
Enumerating a pack
I don't quite understand the base trick from Daisy Hollman's talk:
https://youtu.be/15etE6WcvBY?t=2670
Enumerating a pack using c++20 lamdas with explicit template arguments.
#include
#include
template
Oliver Schönrock
- 1,038
- 6
- 11
1
vote
2 answers
Metafunction to check if all parameter pack arguments are the same
I'm new to template metaprogramming. I was looking for a metafunction to check if parameter pack arguments are of a certain type (C++11 required). For this I use:
template
void foo(Ts... args)
{
static_assert(is_all_same
glades
- 3,778
- 1
- 12
- 34
1
vote
2 answers
How to expand the initializer list parameters pack?
Codes like:
template
void print(type... pack) {
((std::cout << pack << " "), ...);
}
But I have parameters like:
{ {1, 2, 3}, {4, 5, 6} }
So how can I pass this to the function ?
Or, how to expand the parameters pack like…
iEcho-42
- 137
- 1
- 7