62 lines
2.1 KiB
C++
62 lines
2.1 KiB
C++
/**
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* @file llmake.h
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* @author Nat Goodspeed
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* @date 2015-12-18
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* @brief Generic llmake<Template>(arg) function to instantiate
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* Template<decltype(arg)>(arg).
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*
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* Many of our class templates have an accompanying helper function to
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* make an instance with arguments of arbitrary type. llmake()
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* eliminates the need to declare a new helper function for every such
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* class template.
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*
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* also relevant:
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*
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* Template argument deduction for class templates
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* http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0091r3.html
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* was apparently adopted in June 2016? Unclear when compilers will
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* portably support this, but there is hope.
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*
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* $LicenseInfo:firstyear=2015&license=viewerlgpl$
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* Copyright (c) 2015, Linden Research, Inc.
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* $/LicenseInfo$
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*/
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#if ! defined(LL_LLMAKE_H)
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#define LL_LLMAKE_H
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/*==========================================================================*|
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// When we allow ourselves to compile with C++11 features enabled, this form
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// should generically handle an arbitrary number of arguments.
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template <template<typename...> class CLASS_TEMPLATE, typename... ARGS>
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CLASS_TEMPLATE<ARGS...> llmake(ARGS && ... args)
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{
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return CLASS_TEMPLATE<ARGS...>(std::forward<ARGS>(args)...);
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}
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|*==========================================================================*/
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// As of 2015-12-18, this is what we'll use instead. Add explicit overloads
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// for different numbers of template parameters as use cases arise.
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/**
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* Usage: llmake<SomeTemplate>(arg)
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*
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* Deduces the type T of 'arg' and returns an instance of SomeTemplate<T>
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* initialized with 'arg'. Assumes a constructor accepting T (by value,
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* reference or whatever).
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*/
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template <template<typename> class CLASS_TEMPLATE, typename ARG1>
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CLASS_TEMPLATE<ARG1> llmake(const ARG1& arg1)
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{
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return CLASS_TEMPLATE<ARG1>(arg1);
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}
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template <template<typename, typename> class CLASS_TEMPLATE, typename ARG1, typename ARG2>
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CLASS_TEMPLATE<ARG1, ARG2> llmake(const ARG1& arg1, const ARG2& arg2)
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{
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return CLASS_TEMPLATE<ARG1, ARG2>(arg1, arg2);
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}
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#endif /* ! defined(LL_LLMAKE_H) */
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