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Re: Is it Possible to export a class from a DLL? Cedric Moonen6-Jun-03 1:14 Cedric Moonen 6-Jun-03 1:14  Take a look at this article: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncomg/html/msdn_cpptocom.asp[^] It explain in detail everything you'll need to start !! Hope this helps Re: Is it Possible to export a class from a DLL? berndg6-Jun-03 2:29 berndg 6-Jun-03 2:29  Cedric, I think you might be overshooting the target here. COM is one thing, but you might also simply export a C++ coded class with the __declspec(dllexport) statement in MSDEV, and import it with __declspec(dllimport). Of course that technique requires C++ to be used on both sides (unlike COM). Bernd Re: Is it Possible to export a class from a DLL? Cedric Moonen6-Jun-03 2:49 Cedric Moonen 6-Jun-03 2:49  Yep, that's rigtht, but in this case, you'll have to include the .h and the .cpp files from all your classes in the project then! If you use a 'kindof' COM model, you'll just have to include the .h file from the interface (just virtual functions), and then use a global function from the dll that returns a pointer to the base class that is in fact 'a pointer to a specific child class'. So, in that way, you don't have to include .h and .cpp files from all your derived classes. The client program doesn't even know the existence of the derived classes: he just call virtual functions from the base class that are redirected to functions from the derived class. Or, I perhaps misunderstood the question ? Re: Is it Possible to export a class from a DLL? berndg6-Jun-03 2:58 berndg 6-Jun-03 2:58  You didn't misunderstand the question, but the DLL export statement... You have to include header files in both sides (there is no type library query or so), but the code stays on the server side (DLL). Just look at the whole thing as if it were a good old function library, only with dynamic linking, classes, C++, and so forth. This is not a "kindof COM", this is a C++ class library. Plain, simple, and useful. Bernd Re: Is it Possible to export a class from a DLL? geo_m6-Jun-03 3:40 geo_m 6-Jun-03 3:40  But I think, that exporting anything C++ means that the another compiler might not be able to import it (due to different non-standard name mangling) and you must use the same compiler then. But I can be wrong. Re: Is it Possible to export a class from a DLL? berndg6-Jun-03 3:53 berndg 6-Jun-03 3:53  Agreed. Exporting a class from a DLL does not allow for multi-language use, or multi-compiler use. I agree COM is the more powerful tool in places, but it also is an overkill in many others. Bernd Re: Is it Possible to export a class from a DLL? Theopulus6-Jun-03 6:02 Theopulus 6-Jun-03 6:02  Thanks for all the answers, but I'm not looking for a COM interface. Instead of that, I'd like to use plain DLL's, but as I've just read, I'd have to include .cpp files on both sides and that's what I don't want to do. All I want is to give a DLL without giving even the header files. I don't want any .h or .lib. Hope I've explained better this time. Thanks in advance!! __________________________ Fernando de Francisco Cano __________________________ Re: Is it Possible to export a class from a DLL? berndg6-Jun-03 6:15 berndg 6-Jun-03 6:15  Fernando, if you want to ship a library, then you must allow clients to connect to that library. One technique is to use static linkage. To do that, you will ship a .lib file and a header file. Another technique is dynamic linkage, for which you will ship a .DLL and a header file. Finally, you could ship COM controls, which come in the physical form of .DLL or .OCX files. You don't need to include header files because COM provides query mechanisms, but essentially in any case you cannot just ship something without letting your user's compiler know what it is. You seek the impossible unless you don't wish your DLL to be of any use - in which case you could just ship a DLL without a header file Bernd Re: Is it Possible to export a class from a DLL? berndg6-Jun-03 6:17 berndg 6-Jun-03 6:17  ... oh, and in order to get this clarified: you do not ship source code (except header files), unless you wish to. None of the three techniques I listed requires distribution of .cpp files, no whatsoever. B. Re: Is it Possible to export a class from a DLL? Theopulus9-Jun-03 1:03 Theopulus 9-Jun-03 1:03  First of all, thanks a lot for your soon answer . I have to ship .DLL + .h file if I want to use Dynamic linking (as you wrote earlier) but... am I able to use classes from this .DLL? I mean without using COM. Another question: Must I ship the whole .h file? I mean, do I have to ship private, protected and public zones? I'd like to hide private data at least. Thanks in advance. __________________________ Fernando de Francisco Cano __________________________ How to get notification of drag-drop of headers in CListCtrl Wormhole52306-Jun-03 0:21 Wormhole5230 6-Jun-03 0:21  I used extended style LVS_EX_HEADERDRAGDROP. So, I can drag-drop a header. How to get notification of drag-drop of headers in CListCtrl whenever it was changed? Thanks. Re: How to get notification of drag-drop of headers in CListCtrl YoSilver6-Jun-03 4:47 YoSilver 6-Jun-03 4:47  Derive a class from CListCtrl and handle the notifications in the derived class. Smart Card Inserts & Removes Fad B5-Jun-03 22:41 Fad B 5-Jun-03 22:41  Hi, Did any one know how to get a message in Visual C++ when a smart card was inserted or removed ? Thanks Very much CPropertyPage BlackRider5-Jun-03 22:35 BlackRider 5-Jun-03 22:35  The CPropertyPage constructor looks like this CPropertyPage( UINT nIDTemplate, UINT nIDCaption = 0 ); Now the second argument (the UINT nIDCaption) comes from the string table. What if I wanna create multiple tabs from code without knowing how many I'm gonna open. I can't make a string table entry for every tab I wanna make cause I don't know how many I'm going to create. So how can I modify the string that I give to an ID from code ???? Is that possible ? Re: CPropertyPage Rage5-Jun-03 22:47 Rage 5-Jun-03 22:47  It is 0 by default, so only use the first parameter, and the dialog name will be used. Then, once you have created the property page, do : CPropertyPage mypage; mypage.pszTitle="My Title"; And you're done. ~RaGE(); Re: CPropertyPage Cedric Moonen5-Jun-03 22:50 Cedric Moonen 5-Jun-03 22:50  You don't have to specify a value for the second argument (default will be 0). In this case, the title will be taken from the dialog template title! Testing for Power-Off support Ernesto D.5-Jun-03 22:09 Ernesto D. 5-Jun-03 22:09  Hi all, does anyone know how can i test(by code of course) if the computer supports the Power-off (ATX board) feature, or only the Shutdown ("Its now safe to turn off your computer") Feature? Creating a dll Toni785-Jun-03 21:53 Toni78 5-Jun-03 21:53  I would like to write a dll that can be used with VC, VB, Delphi, and Java. The thing is that I can write the source code only with VC or Win32 API, and I don't know how these other languages work. Could I get some feedback on this topic? By the way, I do know that MFC based dlls work only for MFC based programs. // Afterall I realized that even my comment lines have bugs Re: Creating a dll Andrew Walker5-Jun-03 22:11 Andrew Walker 5-Jun-03 22:11  You probably want to write a COM DLL. COM is the standard way of letting any language talk to a software component. Depending on what you need to do you might get away with writing a C# assembly (? I think) For better information on COM check out that message board or check out Mike Dunn's article "Introduction to COM - What It Is and How to Use It.". If you can keep you head when all about you Are losing theirs and blaming it on you; If you can dream - and not make dreams your master; If you can think - and not make thoughts you aim; Yours is the Earth and everything that's in it. Rudyard Kipling Re: Creating a dll Toni785-Jun-03 22:21 Toni78 5-Jun-03 22:21  Thank you very much for your quick reply. I was hoping that I didn't have to write a COM DLL but if there is no other way to do it then COM DLL it is. // Afterall I realized that even my comment lines have bugs Re: Creating a dll Cedric Moonen5-Jun-03 22:46 Cedric Moonen 5-Jun-03 22:46  It depends also of what kind of stuff you want the Dll to do! If you need the dll to generate classes, then you have to write a COM dll. But if the dll just hold some functions, you can use a normal dll (and you can also use MFC dll). It works with Visual Basic but I'm not sure for the other language (I suppose that works too). You have to be aware of calling conventions !! Re: Creating a dll Toni785-Jun-03 22:48 Toni78 5-Jun-03 22:48  Actually I just want to use some normal functions. Is there a website where I can read about the calling conventions? // Afterall I realized that even my comment lines have bugs Re: Creating a dll Cedric Moonen5-Jun-03 22:56 Cedric Moonen 5-Jun-03 22:56  Hmmmm, yes, it must probably exist some but I don't know where ! Perhaps make a search on this site and on google! In fact, the calling convention (stdcall, cdecl, ...) is the way the stack is cleared (by the client or by the dll). If you call a function from an executable that has not the same calling convention from the function inside the dll, you will have some problems! But you can change this calling convention within the client program (or within the dll) so they can match. Re: Creating a dll Toni786-Jun-03 11:15 Toni78 6-Jun-03 11:15  thank you Cedric. // Afterall I realized that even my comment lines have bugs Messaging question Stan the man5-Jun-03 21:38 Stan the man 5-Jun-03 21:38  I was wondering what would be the best way to implement the following: I have many types of objects that have a similar function the same. I want a main Messaging class to route commands to each respective object to do something when something specific happen related to the object. A use for this would be to have multiple graphs that would be plotting different thing with the same data. However the main difference is that I could change things at runtime by attaching this graph to this and that graph to that. Any ideas? Anything I can read to do what I would like? Appreciate any help. Thanks.

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