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/**
* @file llmake.h
* @author Nat Goodspeed
* @date 2015-12-18
* @brief Generic llmake<Template>(arg) function to instantiate
* Template<decltype(arg)>(arg).
*
* Many of our class templates have an accompanying helper function to
* make an instance with arguments of arbitrary type. llmake()
* eliminates the need to declare a new helper function for every such
* class template.
*
* also relevant:
*
* Template parameter deduction for constructors
* http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0091r0.html
*
* https://github.com/viboes/std-make
*
* but obviously we're not there yet.
*
* $LicenseInfo:firstyear=2015&license=viewerlgpl$
* Copyright (c) 2015, Linden Research, Inc.
* $/LicenseInfo$
*/
#if ! defined(LL_LLMAKE_H)
#define LL_LLMAKE_H
/*==========================================================================*|
// When we allow ourselves to compile with C++11 features enabled, this form
// should generically handle an arbitrary number of arguments.
template <template<typename...> class CLASS_TEMPLATE, typename... ARGS>
CLASS_TEMPLATE<ARGS...> llmake(ARGS && ... args)
{
return CLASS_TEMPLATE<ARGS...>(std::forward<ARGS>(args)...);
}
|*==========================================================================*/
// As of 2015-12-18, this is what we'll use instead. Add explicit overloads
// for different numbers of template parameters as use cases arise.
/**
* Usage: llmake<SomeTemplate>(arg)
*
* Deduces the type T of 'arg' and returns an instance of SomeTemplate<T>
* initialized with 'arg'. Assumes a constructor accepting T (by value,
* reference or whatever).
*/
template <template<typename> class CLASS_TEMPLATE, typename ARG1>
CLASS_TEMPLATE<ARG1> llmake(const ARG1& arg1)
{
return CLASS_TEMPLATE<ARG1>(arg1);
}
template <template<typename, typename> class CLASS_TEMPLATE, typename ARG1, typename ARG2>
CLASS_TEMPLATE<ARG1, ARG2> llmake(const ARG1& arg1, const ARG2& arg2)
{
return CLASS_TEMPLATE<ARG1, ARG2>(arg1, arg2);
}
#endif /* ! defined(LL_LLMAKE_H) */
|
