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There are two basic ways to expose a secondary interface:
a) local classes (MFC does that, including some dirty tricks to make this effective)
b) multile inheritance (ATL does that)
b) is IMO much cleaner, only you can get into problems with method name clashes
Some pseudocode for the latter:
class CCoImpl : public IFun, public ITest
{
HRESULT QueryInterface()
{
if (iid == IUnknown) {
addref, return static_cast<IFun *>(this);
}
if (iid == IFun) {
addref, return static_cast<IFun *>(this);
}
if (iid == ITest) {
addref, return static_cast<ITest *>(this);
}
return E_NOINTERFACE;
}
HRESULT GoShopping() { ... }
HRESULT GoRocking() { ... }
HRESULT TestCountShoes(....) { ... }
};
you get the idea...
Neither way you can expose two dispatch (or dual) interfaces - you can only have obe dispatch-based interface per object.
If I could find a souvenir / just to prove the world was here [sighist]
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How can I get the visible area of a window's CDC(In the paint function)?
I am trying to draw a grid, but drawing it on the whole thing would be wasteful(It's big!)
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Huh ?
You normally draw in the client area of a window ( GetClientRect ), should be clipped, for additional clipping, look for them in the CDC help of MSDN.
Max.
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Use the function ::GetRandomRgn with the SYSRGN flag. You may need to download the most current SDK headers in order to use this function.
I have written this article on clipping regions:
http://www.codeproject.com/gdi/cliprgnguide.asp[^]
It describes the system region, clipping region and meta region. It also has an example of how to get the imformation that you are asking for.
Good Luck
Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!
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I'm trying to add the "Generic / Text Only" printer driver programmatically.
I've used AddPrinterDriver and AdPrinterDriverEx from the API but the driver doesn't work.
Did anybody solve this problem or have anybody some suggestions?
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I've got a named pipe. One process writes to its (let's call it A) side, and the other process reads from its oposite (B) side. The process at the B side can randomly connect to and disconnect from the pipe. I'd like to prevent the A-side process from even trying to write to the pipe if the B-side process is disconnected. How can A-side process check the B-side pipe status? I have an idea of using PeekNamedPipe() with all its pointer parameters set to NULL and, when I get return value zero, interpret the result of GetLastError(), but this idea by no means seems that smart to me.
Any suggestions? Is GetNamedPipeHandleState() of any use in these situations?
TIA
Martin
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I did use PeekNamedPipe for this purpose and it worked perfectly.
I use a one byte reciever buffer in the PeekNamedPipe function.
You could of course use WriteFileEx with an completion Routine and wait
for an error to occur.
A live ping always involves sending packets and check if the reciever responds
to it. There is simply no other way to check if somebody has unplugged Your network cable. PeekNamedPipe does exactly this in a transparent way without disturbing
your data transfer.
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Thanks for your reply. Now I know I'm standing on the firm ground. Sometimes it's better to learn from others' successes instead of my own failures. 
Martin
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hi, pretty new to .NET. But just want to make sure that i pick the right tool for a development project.
Project: coporate infrastructure - from scratch. Areas of concern involves: SQL Server 2000 dev/DMO, Active Directory, IIS (web server and FTP), security (Crypto), Exchange Server, Web application/service, WIN 2000 Adv Server.
Why Choose VC?
1. Backward compatibility
2. speed
but since:
1. this is a infrastructure project starting from scratch, we're not really concerned with "backward compatibility"? I presume there'd be no problem integrating COM components into VB.NET code.
2. speed. VB.NET is not any slower than VC.NET.
3. GUI. VB has a much better dialog editor than VC.
Just want to re-confirm my understanding. My preferred development tool for project like this will be VB.NET.
What do u think?
norm
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I have absolutly no experience with VB or any of the technologies you are talking about! so take this with a brick of salt!
There's nothing wrong with either of them.
Use the language that you feel more confortable with! ( this is the most important point ! )
You can always create external DLL in C++ for more computational intensive stuff, or things that are easier made in C++ than in VB.
Some people will suggest using C#.
Max.
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QUOTE: "You can always create external DLL in C++ for more computational intensive stuff,"
sure. but isnt it true that all .NET languages compiled to IL? speed is more or less the same among all .NET languages?
QUOTE 2: "or things that are easier made in C++ than in VB."
any examples?
norm
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norm wrote:
sure. but isnt it true that all .NET languages compiled to IL? speed is more or less the same among all .NET languages?
Yes and no: under C++ you can mix unmanaged and managed code, so you can still generate native code with a ".NET face"
I see dumb people
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Abolish VB!
I will not say anything more... I've said too much about what I think of VB in these forums... 
Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!
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If you want to write managed .NET code, go with C# and use managed C++ for wrapping legacy code.
Don't even think about VB.NET; It is a poor language, has no advantage over C#. There are a lot of bodges in VB.NET to keep old VB programmers happy.
Everything you can do in VB.NET, you can do in C# and C# will give you a more solid code base.
Michael
Fat bottomed girls
You make the rockin' world go round -- Queen
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that's something new. i did play with VB.NET a little, seems very nice and efficient. where can i read up a lil more on how exactly is c# better than VB.NET?
thanks!
norm
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norm wrote:
where can i read up a lil more on how exactly is c# better than VB.NET?
I use both a lot, and I can say there are some strong points favorable to C# over VB.NET:
.C# has a much cleaner syntax. No legacy compatibility to concern about.
.It may seem stupid, but VB IDE has an auto-identing "feature" extremely annoying
.C# has the "using" statement for automatic destruction of IDisposable object instances. VB.NET code will need to use lots of Try/Catch code to do the same thing and is very probable having resource and memory leaks under it.
.C# can go "unsafe" and use pointer manipulation.
.C# can create more than one namespace per project.
.C# can control on code block basis, wether the integer arith. expressions are checked or not.
.C# can stack allocate arrays which will not be garbage collected
.By default, C# is type-safe (Option Strict On), and a clean syntax for type coercion. This is a thing VB programmers will have a hard time catching on.
.VB.NET has a very weird syntax for calling static class members
.VB.NET has two error handling models: some functions will raise errors, other exceptions. This leads to interesting bugs.
.Under C# you can have static class constructors. This can eliminate several "if x is Nothing" statements and reduce coding.
.Signed ("Strong Named") assemblies in C# can generate signed Interop assemblies right from the IDE when calling legacy COM code. Under VB.NET you'll have to resort to tlbimp.
I'm specially concerned about the C# audience and the VB.NET audience. The next version of C# has been already anounced with tons of nice and useful features, like templates, anonymous delegates and iterators. Nothing of these will be available to VB.NET soon, because it's too complicated for VB.NET programmers.
I see dumb people
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quote: "VB.NET has two error handling models: some functions will raise errors, other exceptions. This leads to interesting bugs."
raising errors and throwing exception? arent the two the same?
norm
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norm wrote:
raising errors and throwing exception? arent the two the same?
No, under VB.NET, not, because of backwards compatibility.
I've saw some really scary code some time ago, involving the new "On Error Goto -1" error that demonstrated they are not the same. I don't recall where I saw it, but if I find this sample again, I'll send you.
I see dumb people
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GOTO? didnt know it still exists in dot-net.
thanks =)
norm
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norm wrote:
GOTO? didnt know it still exists in dot-net.
Not only exists, but it needed to be "enhanced":
Local machine MSDN Link
I see dumb people
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Oh, and I almost forgot: C# has a XML documentation feature which can generate a nice documentation, specially for big projects.
I see dumb people
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also, direct memory manipulation in C++, is it available in C#?
can u manipulate individual bit?
what application can u see for this? Communication between Java and C++ over raw socket? what else?
norm
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norm wrote:
also, direct memory manipulation in C++, is it available in C#?
can u manipulate individual bit?
More or less. You can have pointers and manipulate memory with them, but there are some cares that need to be taken, like pinning memory, because the GC is moving memory all the time. And the pointers are checked, which will prevent buffer overflows, memory corruption and GPFs.
Direct bit manipulation? Yes. The syntax is exactly the same of C++. And better, you have some enum candies which can do automatic bit manipulation for you. VB.NET has this too, but with an UGLY syntax.
norm wrote:
what application can u see for this? Communication between Java and C++ over raw socket? what else?
This and imaging. You have GDI+ and can do very fast coding in C# using pointer and image manipulation. Under VB.NET you are doomed to the very slow GetPixel and SetPixel for this.
I see dumb people
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norm wrote:
VB.NET is not any slower than VC.NET.
Actually, VC.NET creates optimised IL code.
Christian
No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002
C# will attract all comers, where VB is for IT Journalists and managers - Michael P Butler 05-12-2002
Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002
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