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Tolua: The Specified Procedure Could Not Be Found.

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Today I was going to make a tiny DLL that binds some C code with tolua++, and I ran into this error message:

lua: error loading module .foo. from file .daisy\debug\foo.dll.:

    The specified procedure could not be found.

That looks like my DLL is not exporting the luaopen_foo function correctly. That is the function lua calls to initialize the package it just opened, and tolua++ was not declaring it properly:

TOLUA_API int luaopen_foo (lua_State *tolua_S) {
    return tolua_foo_open(tolua_S);

TOLUA_API is defined toextern, which doesn.t mean that it will be exported by the DLL, because on windows, the magic incantation for that is__declspec(dllexport). The tolua++ header has no special treatment for Windows, so I.m guessing that problem has just never come up for them.

Once the problem is understood, the solution is easy: I added another function to dllmain.cpp that has the correct export declaration and calls the generated one.

extern "C" {
    int tolua_bar_open(lua_State *);
    int __declspec(dllexport) luaopen_foo (lua_State *L) {
        return tolua_bar_open(L);

There is one caveat, because tolua++ has already created a function named luaopen_foo, so I had to tell it to name things differently, for which there is a command-line argument:

tolua++ -n bar foo.pkg > foo.c