C / C++ / MFC

George_George16-Feb-08 22:33

16-Feb-08 22:33

Thanks CPallini,

Quite interesting, you mean if we write statement like this in VB (later binding),

Dim objSer as Objectset
objSer = CreateObject("MSCOMMLib.MSComm")

during compile/build phase in VB, nothing is checked? Even if the component progID MSCOMMLib.MSComm is not checked?

(if yes, type library is not used at compile/build time)

regards,
George

CPallini16-Feb-08 23:04

CPallini

16-Feb-08 23:04

Exactly, the following code succesfully compiles on my system

Private Sub Command1_Click()
    Dim obj As Object
    Set obj = CreateObject("George.George")
End Sub

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

George_George16-Feb-08 23:32

16-Feb-08 23:32

Thanks CPallini,

My question is answered! You are so knowledgeable! Cool!!

regards,
George

Rajkumar R15-Feb-08 0:14

Rajkumar R

15-Feb-08 0:14

George_George wrote:
once we inherit from IDispatch interface, then it is always a dual interface, right?

why u said so.

George_George wrote:
What type of implementation in C++ for a component is not a dual interface? I can not imagine a sample

I think ur confusion is once derived from IDispatch in C++, u have access through vtbl (atleast of IDispatch) and also through Invoke(), dual implicit and why u need dual keyword. Is it?

George_George15-Feb-08 0:28

15-Feb-08 0:28

Yes Rajkumar,

Rajkumar R wrote:
I think ur confusion is once derived from IDispatch in C++, u have access through vtbl (atleast of IDispatch) and also through Invoke(), dual implicit and why u need dual keyword. Is it?

Sometimes I notice that the component actually implements the dual interface, but in the IDL file, "dual" property is not added to the interface property.

1. Is it good practice?

2. What is the purpose of doing so? Force user to use IDispatch other than efficient vtable?

3. Could we use vtable even if dual property is not added to interface? For example, using QueryInterface to get come component interface (other than IDispatch and IUnknown)? If we could, then it is a dual interface activity -- invoking through vtable.

regards,
George

Rajkumar R15-Feb-08 4:43

Rajkumar R

15-Feb-08 4:43

yes!! I guessed correctly, u misunderstood the concept of dual interface in OA.

direct vtable-based interfaces as u expect are called "custom interfaces" and invocation through IDispatch are called "automation" or "dispatch interfaces" the "custom interfaces" may need to be accessed after a query interface and may needs custom marshalling. Dual iterfaces can be accessed without a query interface and gets standard marshalling support like dispatch interfaces.

a comparison of these 3 interfaces is here [^]

George_George16-Feb-08 22:36

16-Feb-08 22:36

Thanks Rajkumar,

Sorry that I may not made myself understood. My question is, if I do not declare the interface as dual in IDL file, but actually in implementation, I implemented the dual approach.

Could the client of the component (e.g. in case of C++ client) utilize vtable other than through IDispatch?

regards,
George

Rajkumar R17-Feb-08 0:09

Rajkumar R

17-Feb-08 0:09

George_George wrote:
but actually in implementation, I implemented the dual approach.

again, don't confuse it with "custom interface"

George_George wrote:
Could the client of the component (e.g. in case of C++ client) utilize vtable other than through IDispatch?

yes, u can, use queryinterface and get ur "custom interface".

George_George17-Feb-08 0:23

File Comparison in VC++6.0

17-Feb-08 0:23

Thanks Rajkumar,

Seems the dual property does not enforce compile/link/runtime's strong checking about whether or not the component implements dual interfaces (if the component does not implement dual interface, and there will not be any compile/link/runtime error if component only implemeents IDispatch)? Right?

And similar to the situation when we do not add dual, compile/link/runtime does not enforce strong checking and gives warning or error message when client tries to use dual interface (both vtable and IDispatch), right?

regards,
George

seshi_hari14-Feb-08 21:36

seshi_hari

14-Feb-08 21:36

Hi,
I need to compare two text files in VC++6.0, whose contents have been displayed in two richedit controls.Also i need to highlight the differences that exists in the two files......Can any one help me out?

Cedric Moonen14-Feb-08 21:41

Cedric Moonen

14-Feb-08 21:41

See point 2 here[^]

Cédric Moonen
Software developer

Charting control [v1.2]

Rajesh R Subramanian14-Feb-08 21:43

14-Feb-08 21:43

What have you tried so far? Where are you stuck?

seshi_hari14-Feb-08 23:29

seshi_hari

14-Feb-08 23:29

i have displayed the contents of the files in the richeditcontrols.I dont know how to compare the files and highlight the differences in them.The codes which i got by surfing the net just tell whether the files are equal or not.They just return an int or bool value.Here is the place i got struck.

Rajesh R Subramanian15-Feb-08 0:12

15-Feb-08 0:12

I think it's rather a complex task. I don't think you will get the "code" here right away. You may have to look at the XDiff[^] project. Perhaps that would help you.

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

checking for instance validity

Nemanja Trifunovic15-Feb-08 3:54

Nemanja Trifunovic

15-Feb-08 3:54

My condolences. I had to do the exactly same thing some 5 years ago, and ended up with a post "I hate MFC" in the Lounge Smile | :)

Anyway, to find the differences between files, use Longest Common Subseqence Algorithm[^] - that would be the easy part.

Now, for displaying it in the richedit controls - good luck with that Smile | :)

Programming Blog

utf8-cpp

rp_suman14-Feb-08 21:26

rp_suman

14-Feb-08 21:26

How to check the instance of the class is valid or it is not especially in multi threaded program?

Best Regards,
Suman

Cedric Moonen14-Feb-08 21:29

Cedric Moonen

14-Feb-08 21:29

rp_suman wrote:
How to check the instance of the class is valid

What do you mean exactly ? Can you be more explicit please. What does 'valid' mean ?

Cédric Moonen
Software developer

Charting control [v1.2]

Prasanth M V14-Feb-08 23:08

Prasanth M V

14-Feb-08 23:08

Suman,

Plz give more deatils....what is actually men by 'valid'.
It will be better if u provide with some code fragment that u are using.....

Prasanth Smile | :)

Prasanth M V14-Feb-08 23:13

Prasanth M V

14-Feb-08 23:13

HI,

Plz give more deatils....what is actually mean by 'valid'.
It will be better if u provide with some code fragment that u are using.....

prasanth Smile | :)

Maxwell Chen14-Feb-08 23:19

Maxwell Chen

14-Feb-08 23:19

Hi Prasanth, you replied to the wrong person.

Maxwell Chen

Rajesh R Subramanian14-Feb-08 23:48

14-Feb-08 23:48

Maxwell Chen wrote:
you replied to the wrong person.

How dare you call Cedric a wrong person! Poke tongue | ;-P

Maxwell Chen14-Feb-08 23:51

Maxwell Chen

14-Feb-08 23:51

Rajesh R Subramanian wrote:
How dare you call Cedric a wrong person!

Maxwell Chen

rp_suman15-Feb-08 0:53

rp_suman

15-Feb-08 0:53

He might have meant different person,

Best Regards,
Suman Smile | :)

Rajesh R Subramanian15-Feb-08 1:21

15-Feb-08 1:21

There's a thing called pun. And one more thing called "the joke icon". Hmmm | :|

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP