Re: How to Implement DllGetClassObject?? - COM Discussion Boards

Re: how do i know whether an interface is createable or not?

16-Jun-03 0:25

hi there...

i have some interfaces and i need to be able to handle these interfaces by creating the relevant objects in the DllGetClassObject..

But for that i need to know which interfaces are createable..how do i know that???

thanks

regards

J. Schermerhorn16-Jun-03 3:54

J. Schermerhorn

16-Jun-03 3:54

You generally will want to setup if/else logic from within DllGetClassObject to test for the different CLSID's in your server.(The only interfaces you will want to return through DllGetClassObject are IID_IClassFactory or IID_IUnknown since the class factories QueryInterface logic will only be checking for those two identifiers).

For example:

<br />
STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, void** ppv)<br />
{<br />
   HRESULT hr;<br />
   if (rclsid == CLSID_MyFirstCoClass)<br />
   {	<br />
      MyFirstCoClassFactory* pCF1 = new MyFirstCoClassFactory();<br />
      hr = pCF1->QueryInterface(riid, ppv);<br />
      if (FAILED(hr))<br />
      {<br />
         delete pCF1;<br />
      }<br />
   }<br />
   else if (rclsid == CLSID_MySecondCoClass)<br />
   {<br />
      MySecondCoClassFactory* pCF2 = new MySecondCoClassFactory();<br />
      hr = pCF2->QueryInterface(riid, ppv);<br />
      if (FAILED(hr))<br />
      {<br />
         delete pCF2;<br />
      }<br />
   }<br />
   else<br />
   {<br />
      hr = CLASS_E_CLASSNOTAVAILABLE;<br />
   }<br />
   return hr;<br />
}<br />

Hope this answers your question!

-John

Re: how do i know whether an interface is createable or not?

safee ullah16-Jun-03 19:34

How to Implement DllGetClassObject??

16-Jun-03 19:34

Thanks a lot John..

The information you provided was certainly helpful..But i wanted to know that if i have 5 or 6 interfaces already defined with me and i want to determine which of them is cocreateable..how do i know that??
If i know that a specific interface is createable only then will i call it and check for it in the DllGetClassObject..

regards

Anonymous14-Jun-03 1:48

Re: How to Implement DllGetClassObject??

14-Jun-03 1:48

hi there..

i am working on an ole control and need to implement the method DllGetClassObject..
ne ideas???? what to do?

thanks

Anonymous14-Jun-03 2:23

componet for INTERNET EXPLORER programming in .NET?

14-Jun-03 2:23

DllGetClassObject is one of four DLL server exports that are required.

DllGetClassObject exposes class factories for all objects in a given server. This export will return an IClassFactory pointer to the client.

Instantiate a class factory object (using the C++ new operator) and then call QueryInterface to obtain an IUnknown or IClassFactory interface pointer. Check the return value of the QueryInterface invocation with the FAILED or SUCCEEDED macros. If the call failed delete your class factory object and then return the HRESULT.

Regards,

Asim N.13-Jun-03 3:02

Asim N.

13-Jun-03 3:02

hello,
i want to do some IE programming. in .net
but i am not able to have the componet that i should add.
can someone guide me on this.
ASIM

Asim

Visual Studio Add-In --> IApplicationEvents save event

Amir Harel12-Jun-03 4:25

Amir Harel

12-Jun-03 4:25

Hi all, i'm writting a Add-in to the visual studio 6, and i need to catch event before the document is being saved, while the IApplicationEvents supplies DocumentSave which is fired after it was saved.

Does anyone knows how to solve my problem?

Amir Harel
My boss always tell me: Why we always search for the generic solution for a specific problem...

Re: Visual Studio Add-In --> IApplicationEvents save event

Anonymous19-Jun-03 21:37

ItypeInfo::Invoke paramerters

19-Jun-03 21:37

ConnectionPoints.

safee ullah11-Jun-03 23:39

Re: ItypeInfo::Invoke paramerters

11-Jun-03 23:39

hi there
i needed help regarding the first paramenter of the method ITypeInfo::Invoke(
VOID FAR* pvInstance,
MEMBERID memid,
unsigned short wFlags,
DISPPARAMS FAR* pDispParams,
VARIANT FAR* pVarResult,
EXCEPINFO FAR* pExcepInfo,
unsigned int FAR* puArgErr
);

from where or how do i get pvInstance?

thanks
regards

Hans Ruck12-Jun-03 0:37

Re: ItypeInfo::Invoke paramerters

12-Jun-03 0:37

safeeullah wrote:
from where or how do i get pvInstance?

Generally ITypeInfo::Invoke is used to implement IDispatch::Invoke. So, the pvInstance parameter should be the implementing class' this. Something like:

HRESULT __stdcall IDispatch_Derived_Class::Invoke(DISPID dispIdMember, REFIID riid, LCID lcid,
     WORD wFlags, DISPPARAMS* pDispParams, VARIANT* pVarResult,
     EXCEPINFO* pExcepInfo, UINT* puArgErr)
{
  return m_pTypeInfo->Invoke(this, dispIdMember, wFlags,
     pDispParams, pVarResult, pExcepInfo, puArgErr);
}

or the equivalent

HRESULT __stdcall IDispatch_Derived_Class::Invoke(DISPID dispIdMember, REFIID riid, LCID lcid,
     WORD wFlags, DISPPARAMS* pDispParams, VARIANT* pVarResult,
     EXCEPINFO* pExcepInfo, UINT* puArgErr)
{
  return DispInvoke(this, m_pTypeInfo, dispIdMember,
     wFlags, pDispParams, pVarResult, pExcepInfo, puArgErr);
}

rechi

safee ullah12-Jun-03 19:44

InvokeHelper.. More info needed!

12-Jun-03 19:44

thanks a lot..
got it..
Smile | :)

kindest regards
safee

COM exe under win98

Ryszard Krakowiak10-Jun-03 21:20

Ryszard Krakowiak

10-Jun-03 21:20

Hi
I've COM exe server. It registers on WinNT based platforms.
I can't register it under Win98.
It is possible to do this ?

I've error in
_Module.UpdateRegistryFromResource(IDR_AtlExe, TRUE);
hRes is 0x80040154 (class not registered).

In all others calls before _Module.UpdateRe... are ok (hRes is 0).

I use VC 6 with sp5 and simple code generated from ATL wizard with one interface with one method.

Thx 4 Hlp

harinath10-Jun-03 19:16

harinath

10-Jun-03 19:16

InvokeHelper() function...

//MSDN says
This method calls the object method or property specified by dwDispID, in the context specified by wFlags. The pbParamInfo parameter specifies the types of the parameters passed to the method or property. The variable list of arguments is represented by ... in the syntax declaration.

well, that is what MSDN says about InvokeHelper method of COleDespatcher class.

Now My confusion is....

I am trying to understand a project, which is an activex control whose purpose is to display some graphical interface to the data given from a server.

Here the OCX project is using another library which is a wrapper for another library, customized to the requirements of OCX project.

When I tried to trace how the flow of function call is going on..
it is happening like this..

my ocx project is calling method from wrapper project which is using InvokeHelper(..).
my collegue says "it is all com funda".. and he showed me a method in another project where actual code is present.
The function call is something like this.

InvokeHelper(0xa, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms,<br />
	iTraceNumber, &strTraceId, strSource);<br />

But How do I come to know what is happening here..
it is all confusing.

any ideas..?
meanwhile I try to go thru the COM section of codeguru and codeproject.

Thanx in advance

Harinath

Harinath Reddy
HOneywell Technology Solutions Lab,
Bangalore,
India-560076

How call the javascript 'escape' function from C++ ?

Thierry Maurel10-Jun-03 7:24

Thierry Maurel

10-Jun-03 7:24

Hello,
is there a simple way to call the javascript escape function from c++ app (mfc)?
I need to generate a html slideshow from a selection into a database, but it seems that certains strings (valid in c++) can be invalid in the html file.
For ex : "\\test\\" in c++ are generated into "\test\", so the last \" break the string Wink | ;-)

So my idea is to add an unescape into the generated html, but the counterpart is a call to escape in the c++ part...
I already embed an IE browser in my application.

Another bad point is that all calls are in a loop, so I want to avoid slow calls !
Thanks in advance

Thierry
Isotools Software Engineer

IDispatch, ITypeInfo et al

Jörgen Sigvardsson10-Jun-03 2:26

Jörgen Sigvardsson

10-Jun-03 2:26

Could someone enlighten me on how to retrieve the name of an object implementing IDispatch? With the name I mean the coclass-name as specified in the IDL-file.

--
"It's a condition of mental divergence, I find myself on the planet Olgo part of a intellectual elite, prepared to subjugate the barbarian hordes on Pluto, but even though this is a totally convincing reality for me in every way, nevertheless Olgo is actually a construct on my psychee. I am mentally divergent in that I am escaping certain unnamed realities that plague my life here."

Re: IDispatch, ITypeInfo et al

Hans Ruck11-Jun-03 22:11

COM/OLE people..how to fetch controllingunknown 's outer unknown?

11-Jun-03 22:11

See the implementation of XYDispDriver::LoadTypeInfo in XYDispDriver.cpp from this article[^]'s sources. It's not exactly what you need but could be a good starting point.

rechi

safee ullah10-Jun-03 1:00

Accessing constants via vb-script ?

10-Jun-03 1:00

hi there..
i am quite a situation here..

how do i get to the outer unknown of the controlling Unknown?

HELP..

regards

Accessing Outlook

Madmaximus9-Jun-03 6:49

Madmaximus

9-Jun-03 6:49

Hi everyone,

I get the following error message from Outlook when I try the saveas command: “Unable to coerce parameter value: Cannot translate your string”.
Code example:

szFunc = OLESTR("SaveAs");

hr = m_pDisp->GetIDsOfNames(IID_NULL,
&szFunc,
1,
LOCALE_SYSTEM_DEFAULT,
&dispID);
if (FAILED(hr))
{
cout << "GetIDsOfNames failed on SaveAs";
return;
}

CComVariant vPath(strPath.GetString());
CComVariant vType(Outlook:lMSG);

VARIANT pVal[2];

dp.cArgs = 2;
dp.cNamedArgs = 0;
dp.rgdispidNamedArgs = 0;
dp.rgvarg = pVal;
pVal[1].vt = VT_ERROR;
pVal[1].scode = DISP_E_PARAMNOTFOUND;
pVal[0].vt = vPath.vt;
pVal[0].bstrVal = vPath.bstrVal;

EXCEPINFO excep;
hr = m_pDisp->Invoke(dispID,
IID_NULL,
LOCALE_SYSTEM_DEFAULT,
DISPATCH_METHOD,
&dp,
NULL,
&excep,
NULL);
if (FAILED(hr))
{
cout << "Invoke failed on SaveAs";
ErrHandler(hr, excep);
return;
}

Any help would be greatly appreciated. Wink | ;)

Thanks,
Ken

Brian van der Beek5-Jun-03 22:51

Brian van der Beek

5-Jun-03 22:51

Hi, I have an application with some disptach interfaces. I can access these interfaces via vb-script without any problems, but when I use constants (I defined an enum) vb-script does not seem to recognize them. The weird part is that I have a function that returns an enum value and that value is received correctly in my vb-script, but when I do a compare with the enum constants, all constants are 'Empty'.

Anyone knows what the problem is? Must I do someting other than just declaring an enum in my idl file?

Re: Accessing constants via vb-script ?

Hans Ruck6-Jun-03 4:11

Re: Accessing constants via vb-script ?

6-Jun-03 4:11

You can't access anything from the idl but some of the coclasses. Probably the enum constants are implicit variables; have you declared Option Explicit in the script?

Brian van der Beek wrote:
The weird part is that I have a function that returns an enum value and that value is received correctly in my vb-script

It works because the enumeration is VARIANT-compatible. Try with a struct and see how it fails.

rechi

Anonymous6-Jun-03 4:24

Re: Accessing constants via vb-script ?

6-Jun-03 4:24

I'm relatively new to scripting and did not know about Option Explicit, it makes this a lot more clear.

I did some more digging and found out that you indeed cannot use constants/enums from a idl/tlb. You should be able to do this when you do early binding (e.g. Dim excel as exec.application), but I don't think you can do this in vb-script.

Hans Ruck6-Jun-03 4:38