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Questions tagged [variadic-templates]

Variadic templates are templates that take a variable number of parameters.

Some programming languages, like D and C++ since with the C++11 standard, support templates that take a variable number of parameters. Variadic templates are useful in a number of situations, for example, defining type-safe heterogeneous containers such as tuples and expanded metaprogramming library facilities.

http://en.wikipedia.org/wiki/Variadic_templates

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Make variadic macro / method which prints all variables names and values

An existing macro gets variadic number of variables on my application. I want, using this macro, to print these variables by name=value format. Here is a small example : #define EXISTING_MACRO(...) < ??? > int main() int a = 0; int b = 1; int c =…
SagiLow
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C++11 variadic template + inheritance

I would like to write an abstraction of linear superpositions using variadic templates. To do that, I would like to define a base type that exhibits a certain form of operator() like so template class…
sblatt
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Variadic alias template to non-variadic class template

In trying to write a simple example for currying of metafunction classes, I wrote the following: #include struct first { template using apply = T; }; template struct…
Barry
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Why does the variadic template argument deduction fail for this function pointer?

In the following minimal example, S::foo works, but S::bar fails. The only difference is the order of the parameter packs Ts and Us. struct FPtr and S::lol are the best workaround I've found, but it's rather uncomfortable to use in practice. Why…
mic_e
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Variadic Templates and RValue refs

Consider the following C++ code template void f (const int x, const int y, Args&&... args) { // Do something } As far as I understand,Args here could either be lvalue or rvalue references, depending on the type deduction at…
ssb
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C++ template sort

I'm looking for template code to sort template parameters, something like: template list sort(T first, Args ... rest) All the types in Args are actually T, but I need to use variadic templates, so that I can small…
Frank
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A structure that stores its fields by size

I would like to know how can I do the following in C++: Consider these classes : C1 < C2 < C3 < ... < Cn, Ci < Cj means sizeof(Ci) < sizeof(Cj) I want a structure that uses variadic templates as a sequence of Ci's, OrderBySize, for…
Othman Benchekroun
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Variadic template unrolling to std::tuple

I have a filter class that takes two template parameters, the number of inputs and the number of outputs. template class Filter { // implementation }; Sometimes I need to chain multiple filters in series so I was thinking to…
dominiktomicevic
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Variadic template method and std::function - compilation error

I'm sure the error is very simple and silly, but I can't see one. Here's the code: #include template class Foo { public: template void exec(const std::function& task,…
Violet Giraffe
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Variadic Template Parameter Packs with Alternating Types

I was wondering if it is possible to capture an alternating parameter pattern using a parameter pack. For example, template class foo { public: foo() : my_T(nullptr), my_U(U) {} …
armstrhu
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Variadic template function name lookup fails to find specializations

I am attempting to program a string concatenation function which utilizes my 3D library's string conversion functions, implemented with a variadic template. The library's conversion function behaves unusually if a string (either const char[] literal…
user3995702
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Expanding container to parameter pack

Let's say I have a variadic function I can't change like so: void Func(int count, ...) { /*etc.*/ } And I'm writing a variadic template like so to wrap that function and make it safer to use: template void ToString(T... args) { …
HTAPAWASO
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Weird overload resolution with variadic function templates

I have the following code: #include template void f(int a, int b, Args... args) { std::cout << b << '\n'; f(a, args...); } void f(int, int b) { std::cout << b << '\n'; } int main() { f(1, 2); …
Lingxi
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C++: Using type as map key introduces template substitution errors

I'm using a tuple as a key to track elements in a map, and then later iterating over the map to produce a string version of the map. To help me with the conversion, I have a template convenience function that will concatenate the tuple used as the…
sabreitweiser
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Variadic Template simulating "runtime" expansion

I have a function that I am trying to convert it to use variadic templates. Unfortunately, the template expansion causes problems when attempting to strongly type the functions during compile time. Here is the old…
user3072517
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