is there anyone familiar with COM? I met problem when changed project from MFC to Qt

[SGaist]

Hi,

You should give more details about what you are using and how you are using it.

[opengpu]

in that dll, it fail to CoInitializeEx

APIImp::APIImp():m_pData(NULL)
{
	//if(!SUCCEEDED(CoInitialize(NULL)))
	if(!SUCCEEDED(CoInitializeEx(NULL, COINIT_MULTITHREADED)))
	{
		assert(0 && "fail to CoInitializeEx");
		return;
	}

[SGaist]

So it's a dll you have control over ?

[opengpu]

yes, i have the dll project, and i added that assert.
but i donot think i can change the code.

[opengpu]

why CoInitializeEx fail in tha DLL? it works in MFC app, and i also donot see anything init or special work.
sorry, i am not quite familia with COM

[opengpu]

@SGaist better donot change the DLL code...

[SGaist]

Do you have several calls to CoInitializeEx ?
Are you properly calling CoUninitialize when you're done with your COM stuff ?

[opengpu]

@SGaist said in anyone familiar with COM? i met problem when changed project from MFC to Qt:

CoInitializeEx

just one time in DLL

APIImp::~APIImp()
{
	release();
	CoUninitialize();
}

[opengpu]

class APIImp {
private:
DataCOMLib::_DataCOMPtr	m_pData;

[opengpu]

CppAPIImp::initialize()
{
CreateInstance(__uuidof(DataCOMLib::DataCOM), NULL, CLSCTX_ALL);
QueryInterface
FindConnectionPoint
QueryInterface
Advise

[opengpu]

APIImp::release()
{
cancelRequest
Unadvise
Release

[hskoglund]

Hi, what error do you get from your CoInitializeEx() call? Try something like:

HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
qDebug() << hr;

[opengpu]

@hskoglund that DLL with COM is not Qt program...

[mrjj]

@opengpu
Hi
then use std::cout to show the HRESULT.
It can give hints about why its not loading,.

What im a bit puzzled about if that is the same DLL used in the MFC app, and you did not change
the actual DLL code. why should it then stop working?

[opengpu]

the DLL is the same...
and i wiil log out the errorcode

[opengpu]

anyone familiar ?

[mrjj]

@opengpu
did you get HRESULT hr out ?

[opengpu]

@mrjj HRESULT = -2147417850

[mrjj]

@opengpu
ok. super. Hopefully mr hskoglund can get something out of that.

[aha_1980]

https://en.m.wikipedia.org/wiki/HRESULT describes tools to decode HRESULTs