In computer science, an operator or function is variadic if it can take a varying number of arguments; that is, if its arity is not fixed.
Questions tagged [variadic]
668 questions
5
votes
2 answers
Solving the mixin constructor problem in C++ using variadic templates
I've recently tackled the constructor problem, where various mixins classes that decorate each other (and a topmost host class) have different constructor signatures. To maintain a single constructor in the resulting decorated class, and without…
Eitan
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5
votes
3 answers
Create hash queue with variadic template
I want to build a hash code queue using variadic template.
The minimal example code is
template
void hash_queue(queue& q){
q.push( typeid(T).hash_code() );
}
template
void hash_queue(queue&…
ztik
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5
votes
3 answers
Variadic helper function with partial argument pack
In the following code:
#include
struct Base {
virtual ~Base() = default;
template void helper (void (T::*)(Args..., int), Args...);
void bar (int n) {std::cout << "bar " << n <<…
prestokeys
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5
votes
1 answer
How to code a variadic defmulti/defmethod in clojure
I have a defmulti/defmethod group that take pairs of arguments like so...
(defmulti foo "some explanation" (fn [arg1 arg2] (mapv class [arg1 arg2])))
(defmethod foo [N P] (->L 1 2 3))
(defmethod foo [L P] (->N 5))
(defmethod foo [P N] (->L 6 7 8))
…
phreed
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5
votes
2 answers
Perfect-forwaring of the variadic template parameters of a struct
In my C++11 code, I have a variadic struct and a function that should use perfect-forwarding for the struct's variadic types such as this:
template
struct S
{
void X(T&&... args)
{
Do(std::forward(args)...);
…
Axel Habermaier
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5
votes
1 answer
Forward variadic function arguments to variadic function using C++11
I want to forward calls to a library which has a variadic method. The simplest example I could come up with to replicate the problem is this:
void Bar(int useless, ...)
{
//Does something
}
template
void Foo(int useless, Args...…
ChrisWard1000
- 526
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- 15
5
votes
3 answers
Can a variadic template match a non-variadic template parameter?
Consider the following snippet:
template class T,class U>
struct apply
{
typedef T type;
};
typedef apply::type tuple_of_one_int; //Should be std::tuple
GCC 4.8.2. says:
type/value mismatch at argument…
sbabbi
- 11,070
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5
votes
2 answers
Is it possible to generate a parameter pack?
Consider the following pseudo code :
template
struct worker : unique::type...{};
struct x{};
struct y{};
struct z{};
Is it possible to write a template unique such that it generates a parameter pack consisting of only unique types…
user1436623
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5
votes
1 answer
Concatenation of tokens in variadic macros
In C, is it possible to concatenate each of the variable arguments in a a variadic macro?
Example:
MY_MACRO(A, B, C) // will yield HDR_A, HDR_B, HDR_C
MY_MACRO(X, Y) // will yield HDR_X, HDR_Y
The normal ## operator has special meaning for…
jbourne
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5
votes
2 answers
Can variadic expansions be used as a chain of comma-operator calls?
I was looking at "How to properly use references with variadic templates," and wondered how far comma expansion can go.
Here's a variant of the answer:
inline void inc() { }
template
inline void inc(T& t, Args& ...args)…
CTMacUser
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4
votes
2 answers
C++ Paramater pack expansion over chained function calls
It is common for libraries to have types which return instances of themselves from member functions to encourage chaining calls. For example, nlohmann json:
auto my_data = my_json_object["first key"]["second key"];
Is there some way to call a…
xzaton jw
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4
votes
2 answers
C++ Instantiate Template Variadic Class
I have this code:
#include
template
void processAll() {
P p = P();
p.process();
}
class P1 {
public:
void process() { std::cout << "process1" << std::endl; }
};
int main() {
processAll();
return…
Dbi
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4
votes
3 answers
Smart variadic expansion based on format string
I have a daemon that reads a configuration file in order to know where to write something. In the configuration file, a line like this exists:
output = /tmp/foo/%d/%s/output
Or, it may look like this:
output = /tmp/foo/%s/output/%d
... or simply…
Tim Post
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4
votes
3 answers
variadic template method to create object
I have a variadic template method inside a template class (of type T_) looking like this
template < typename T_ >
class MyContainer {
public:
...
template
ulong add (A &&...args)
{
T_ t{args...};
// other stuff…
Elle
- 305
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4
votes
2 answers
C/C++ build a generic stack frame to call different callback functions
I'm refactoring a C++ application that refers to a bunch a multiple callback functions, each having a different number of arguments and I would like to know if there's a generic way to build a dedicated argument stack frame before calling each of…
Obsidian
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