I have a SOM DLL. How do I register it?

Here's an example I use for registering. It checks if the DLL is valid before continuing:

#define INCL_WPCLASS
#define INCL_WIN
#define INCL_DOS
#include <os2.h>
#include <string.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
   HMQ hmq;
   HAB hab;
   CHAR szText[256];
   USHORT usResponse;
   CHAR szLoadError[128];
   HMODULE hmod;
   APIRET rc;

   if (argc != 3)
     return 0;

   hab = WinInitialize(0);
   hmq = WinCreateMsgQueue(hab, 0);

   WinDeregisterObjectClass(argv[1]);

   sprintf(szText, "Register %s DLL '%s'?", argv[1], argv[2]);
   usResponse = WinMessageBox(HWND_DESKTOP, HWND_DESKTOP, szText,
      "Register WPS Class", 0, MB_YESNO | MB_MOVEABLE | MB_ICONQUESTION);

   if (usResponse != MBID_YES)
     return 0;

   rc = DosLoadModule(szLoadError, sizeof(szLoadError), argv[2], &hmod);

   if (rc != 0)
   {
     sprintf(szText, "Return code = %u, error module = '%s'.",
             rc, szLoadError);
     WinMessageBox(HWND_DESKTOP, HWND_DESKTOP, szText,
                   "DosLoadModule Failed", 0,
                   MB_ENTER | MB_MOVEABLE | MB_ERROR);

     return 0;
  }


  if (WinRegisterObjectClass(argv[1], argv[2]))
  {
    if (WinCreateObject(argv[1], argv[1], " ",
        "<WP_DESKTOP>", CO_REPLACEIFEXISTS))
      WinMessageBox(HWND_DESKTOP, HWND_DESKTOP, "Created.",argv[1],
                    0, MB_ENTER | MB_MOVEABLE | MB_INFORMATION);
    else
    {
      DosFreeModule(hmod);
      WinMessageBox(HWND_DESKTOP, HWND_DESKTOP, "Failed.",argv[1],
                    0,MB_ENTER | MB_MOVEABLE | MB_ERROR);
    }
  }
  else
  {
    DosFreeModule(hmod);
    WinMessageBox(HWND_DESKTOP, HWND_DESKTOP, "Registration failed.",
                  argv[1], 0,MB_ENTER | MB_MOVEABLE | MB_ERROR);
  }

  return 0; }

FYI, when WPS registers your DLL with SOM, SOM checks if your DLL has a module entry point called SOMInitModule. If it does, it is called (most use SOMInitModule for registering DLLs that have more than one class). Otherwise, it checks for YourClassNewClass, and tries to call it (where 'YourClass' is the parameter you specified on the WinRegisterObjectClass). SOM generates 'YourClassNewClass' in the .IH file; if you're still stuck, verify it is being called and that it doesn't fail (eg, because of version number check).

I suggest registering with a full DLL filespec, eg, C:\MYSTUFF\MYCAR.DLL. Saves on the length of the LIBPATH.

Credit: Dan Kehn