[C] Winapi Call Dynamically and easily

[bugficks]

just for the fun of it, a c++14 version

PHP Code:

#include <string>
#include <memory>
#include <map>
#include <system_error>

template <typename F, typename... ArgTypes>
auto DynCallT(LPCTSTR libName, LPCSTR funcName, ArgTypes... args)
{
    using tstring = std::basic_string<TCHAR, std::char_traits<TCHAR>, std::allocator<TCHAR>>;
    using lib_ptr = std::shared_ptr<std::remove_pointer_t<const HMODULE>>;
    using lib_map = std::map<const tstring, lib_ptr>;

    static lib_map libMap;

    HMODULE h = nullptr;
    const auto &l = libMap.find(libName);
    if(l != libMap.end())
        h = l->second.get();
    else if((h = ::LoadLibrary(libName)) != nullptr)
        libMap[libName] = lib_ptr(h, ::FreeLibrary);
    else
        throw std::system_error(std::make_error_code(std::errc::invalid_argument));

    F f = reinterpret_cast<F>(::GetProcAddress(h, funcName));
    if(!f)
        throw std::system_error(std::make_error_code(std::errc::function_not_supported));

    return f(args...);
} 


usage:

PHP Code:

    // using 'decltype' when you have a prototype 
    auto r = DynCallT<decltype(&MessageBoxA)>(_T("user32"), "MessageBoxA", nullptr, "123", "321", 0);

    // or using func decl as template arg
    auto tc1 = DynCallT<DWORD(WINAPI*)()>(_T("kernel32"), "GetTickCount");

    // using "i dont give a shit" decl :)
    auto tc2 = DynCallT<void*(WINAPI*)(...)>(_T("kernel32"), "GetTickCount", 1, "asd");

    void WINAPI blub(DWORD);
    DynCallT<decltype(&blub)>(_T("kernel32"), "Sleep", 0); 


[mcp]

What is C++14 specific about this code?
One drawback is that it's not thread safe.