CODEWITHSUNDEEP
c++visual-c++
wsy
wsy

Reputation: 289

How to encapsulate this code as a function in c++?

HINSTANCE hDll = LoadLibrary(_T("Test1.dll"));
if (NULL ！= hDll)
{
    typedef CTest1Dlg*(*pDllFun)(int val);
    pDllFun pDlg = (pDllFun)GetProcAddress(hDll, "ShowDlg");
    if (NULL ！= pDlg)
    {
        pDlg(val);
    }
}

Mainly: typedef CTest1Dlg*(*pDllFun)(int val);

The only difference in this line of code is that CTest1Dlg is different, it will become CTest2Dlg or other, but their parameters are the same

Upvotes: 0

Views: 75

Answers (1)

molbdnilo
molbdnilo

Reputation: 66371

This suits a function template.

The most straightforward parametrization would probably be

template<typename Dlg>
void testDllFunction(LPCTSTR dll, const char* name, int val)
{
    HINSTANCE hDll = LoadLibrary(dll);
    if (hDll != NULL)
    {
        typedef Dlg*(*pDllFun)(int);
        pDllFun pDlg = reinterpret_cast<pDllFun>(GetProcAddress(hDll, name));
        if (pDlg ！= NULL)
        {
            pDlg(val);
        }
    }
}


// ...

testDllFunction<CTest1Dlg>(_T("Test1.dll"), "ShowDlg"));

But it's probably a good idea to separate the loading of the function from the calling of it.
Here's one suggestion for that:

template<typename Dlg>
using DlgFunction = Dlg*(*)();

template<typename Dlg>
bool loadFunction(LPCTSTR dll, const char* name, DlgFunction<Dlg>& fun)
{
    HINSTANCE hDll = LoadLibrary(dll);
    if (!hDll)
        return false;
    fun = reinterpret_cast<DlgFunction<Dlg>>(GetProcAddress(hDll, name));
    return fun != NULL
}

// ...

DlgFunction<CTest1Dlg> test1;
if (loadFunction(_T("Test1.dll"), "ShowDlg", test1))
    test1(12);
DlgFunction<CTest2Dlg> test2;
if (loadFunction(_T("Test2.dll"), "Kittens", test2))
    test2(34);

Upvotes: 3

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