🚀 go-pugleaf

Hi Nick,

"nicolasr" <nicolasrNOSPAMATSIGNgmx.net> wrote:
>Hi,
>
>I'm writing a vcl component that needs to initialize COM for multi-threading
>to talk to WMI. I call CoInitializeEx in its constructor like this (only at
>runtime, though!)
>
>CoInitializeEx(0, COINIT_MULTITHREADED);
>
>When I use a simple test project, drag the component on the blank form and
>run it I get this error:
>RPC_E_CHANGED_MODE
>with message string
>"Cannot change thread mode after it is set"
>
>Why? I used a blank project and I don't assume that COM is initialized by
>default?
>

You can try follow solution:
Add comobj.hpp in project .cpp file:

...
#include <comobj.hpp>
#include <vcl.h>
...


Then add variable CoInitFlags in the same cpp:

WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
{
//It will work only for NT/2000/XP but you should set it because WMI as
//a rule need in CoInitializeEx(0, COINIT_MULTITHREADED)
CoInitFlags=COINIT_MULTITHREADED;

Now you can use it in another units:
hres = CoInitializeEx(0, COINIT_MULTITHREADED); //Initialize COM.
if (FAILED(hres))
   { ShowMessage("Failed to initialize COM library. Error code = "+IntToHex((int)hres,8));
     Application->Terminate();
     return;
   }

Just this way I do it in my WMI samples:
http://codecentral.borland.com/codecentral/ccweb.exe/listing?id=19443


Small explanation and comments you can find in VCL comobj.pas:
{ CoInitFlags determines the COM threading model of the application or current
  thread. This bitflag value is passed to CoInitializeEx in ComServ initialization.
  Assign COINIT_APARTMENTTHREADED or COINIT_MULTITHREADED to this variable before
  Application.Initialize is called by the project source file to select a
  threading model.  Other CoInitializeEx flags (such as COINIT_SPEED_OVER_MEMORY)
  can be OR'd in also.  }
var
  CoInitFlags: Integer = -1;  // defaults to no threading model, call CoInitialize()

Vladimir.