variadic-argument-picker-test.cpp File Reference

verify metaprogramming manipulation on a variadic parameter pack. More...

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Description

verify metaprogramming manipulation on a variadic parameter pack.

The unittest VariadicArgumentPicker_test calls a variadic function with different number of arguments and it employs variadic-helper.hpp to alter the order of passed arguments.

The primary difficulty when dealing with variadic templates is the fact that a variadic parameter pack is not a first class type, rather a special language construct which can only be used to perform a pattern match. For this reason, metaprogramming has to proceed "backwards", by invoking a delegate template, thereby dissecting the parameter pack by a pattern match. The key technique for more elaborate manipulation is to construct a variadic index sequence as a helper, and then to expand that index sequence to drive instantiation of a helper template on individual arguments.

See also

variadic-helper.hpp

path-array.hpp

TypeSeqManipl_test

TupleRecordInit_test

TypeListManip_test

Definition in file variadic-argument-picker-test.cpp.

#include "lib/test/run.hpp"
#include "lib/meta/variadic-helper.hpp"
#include "lib/format-string.hpp"
#include "lib/format-cout.hpp"
#include "lib/format-util.hpp"
#include <utility>

Namespaces
namespace	lib
	Implementation namespace for support and library code.
namespace	lib::meta
namespace	lib::meta::test
namespace	lib::meta::test::anonymous_namespace{variadic-argument-picker-test.cpp}

Classes
struct	N< n >
class	VariadicArgumentPicker_test

Functions
template<class... ARGS>
string	fun (ARGS &&...args)
	Variadic test function to invoke.
	LAUNCHER (VariadicArgumentPicker_test, "unit common")
	Register this test class...