Can managed C++ be trusted to handle the garbage collector correctly in the
right bit if I have a project with unmanaged and managed parts in it?
24  2773 
Yes.
Is there something more specific you are after?
Ronald Laeremans
Visual C++ team
"songie D" <so****@D.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl... Can managed C++ be trusted to handle the garbage collector correctly in
the
right bit if I have a project with unmanaged and managed parts in it?
> Yes.
OK, good! I'd heard rumours that you "constantly have to worry about what
the gc's doing", but I've not ran into any problems with that, as yet.
Is there something more specific you are after?
ermm...yes, now you come to mention it.
I'm trying to add
using namespace System::Runtime::InteropServices;
to my project, but it gives the error
C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinBase.h(3139) : error C2872: 'FILETIME' :
ambiguous symbol
could be 'C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinDef.h(354) : _FILETIME FILETIME'
or 'stdafx.cpp(0) : System::Runtime::InteropServices::FILETIME'
many times. I can get round it by putting the explicit namespace name
preceeding all calls to the namespace, but that's a bit cumbersome. Any idea
how I can resolve it?
Also, for having an unmanaged function in one separate .cpp file, and the
managed code in what the IDE gives you (i.e. Form1.h), how would I link to
the unmanaged function, using extern "C"? or other?
Would I have to put #pragma unmanaged round the declaration?
Ronald Laeremans
Visual C++ team
"songie D" <so****@D.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl... Can managed C++ be trusted to handle the garbage collector correctly in
the
right bit if I have a project with unmanaged and managed parts in it?
Songie, ermm...yes, now you come to mention it.
I'm trying to add
using namespace System::Runtime::InteropServices;
to my project, but it gives the error
C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinBase.h(3139) : error C2872: 'FILETIME' :
ambiguous symbol
could be 'C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinDef.h(354) : _FILETIME FILETIME'
or 'stdafx.cpp(0) : System::Runtime::InteropServices::FILETIME'
many times. I can get round it by putting the explicit namespace name
preceeding all calls to the namespace, but that's a bit cumbersome. Any
idea how I can resolve it?
Using a typedef is a simple way around it:
typedef System::Runtime::InteropServices::FILETIME NETFT;
NETFT tm....;
Also, for having an unmanaged function in one separate .cpp file, and the
managed code in what the IDE gives you (i.e. Form1.h), how would I link to
the unmanaged function, using extern "C"? or other?
Header files would work just fine.
Would I have to put #pragma unmanaged round the declaration?
nope. You might want to put it on the definition of the function if you
really want to ensure the compiler generates x86 code (instead of CIL) for
it, though (although you could simply compile the containing .cpp file
without /clr, as well).
--
Tomas Restrepo to****@mvps.org
Your problem is you are including a header, probally windows.h, after the using namespace statement. Just put all your includes before the using namespace statements to get rid of the errors
There are some other problems with using the windows.h file and .Net in the same file. For example MessageBox is a macro, so if your trying to get System::Windows::Forms::MessageBox, you may find the compilier looking for System::Windows::Forms::MessageBoxA. To get around this you have to use #undef for the macro after including the header. This one is only a problem if you try to use MessageBox.
There are no files with '#include' statements AND 'using namespace' statements
The 'Form1.h' has 'using namespace' statements, and the stdafx.h has '#include <windows.h>'
There's no file in which there's both.
How would I compile one file without /clr and the rest with /clr, while building the project all at once?
"Ronald Laeremans [MSFT]" <ro*****@online.microsoft.com> wrote in message news:<#Z**************@TK2MSFTNGP09.phx.gbl>... Yes.
Is there something more specific you are after?
Well, I must say I ran into a few problems with mixed MC++ / C++ when
you make heavy use of the RAII idiom : the .NET runtime seems to have
difficulties with tracking lifetime of parameters, which can have some
nasty side effects, even i f they are not related to GC.
See http://groups.google.com/groups?hl=f....vc.language.*
for the last dirty one.
Arnaud
MVP - VC
Songie, How would I compile one file without /clr and the rest with /clr, while
building the project all at once?
Select the file in question in solution explorer, and use the properties
dialog box to configure compiler arguments.
--
Tomas Restrepo to****@mvps.org
mmm... ok. You can do this, yes
I've given up on using managed c++ anyway now, it seems that passing arrays is a whole lot more difficul
than it is in c#, even though its in the same assembly. See further up posts.
Your problem could be across multiple header files. For example, if your stdafx.h file includes the form1.h file before it includes the windows.h file it would cause the problem. If you look at the compilier output it should give the source file it was working on when it got the error. Looking at the order of includes from this file (and the files included by it) you might find the problem. You can also try changing the order of includes to see if it helps
Header file conficts can be very tough to resolve because the compilier gives no information about what it has done to get there. I try to make it a habbit to avoid the things that can cause them. In this case I avoid "using namespace" statements in my header files. This leads to some rather verbose headers as every type needs an explicit namespace
That's bollocks, there's no way you're supposed to change what's in the
contents of the system files. This isn't anything I've defined!
"Tomas Restrepo (MVP)" <to****@mvps.org> wrote in message
news:OX*************@tk2msftngp13.phx.gbl... Songie,
ermm...yes, now you come to mention it.
I'm trying to add
using namespace System::Runtime::InteropServices;
to my project, but it gives the error
C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinBase.h(3139) : error C2872: 'FILETIME' :
ambiguous symbol
could be 'C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7\PlatformSDK\Include\WinDef.h(354) : _FILETIME FILETIME'
or 'stdafx.cpp(0) : System::Runtime::InteropServices::FILETIME'
many times. I can get round it by putting the explicit namespace name
preceeding all calls to the namespace, but that's a bit cumbersome. Any
idea how I can resolve it?
Using a typedef is a simple way around it:
typedef System::Runtime::InteropServices::FILETIME NETFT;
NETFT tm....;
Also, for having an unmanaged function in one separate .cpp file, and
the managed code in what the IDE gives you (i.e. Form1.h), how would I link
to the unmanaged function, using extern "C"? or other?
Header files would work just fine.
Would I have to put #pragma unmanaged round the declaration?
nope. You might want to put it on the definition of the function if you
really want to ensure the compiler generates x86 code (instead of CIL) for
it, though (although you could simply compile the containing .cpp file
without /clr, as well).
--
Tomas Restrepo
to****@mvps.org
ah, so you're a non-truster I see aswell :-)
I think I'll join you.
It does all seem like a big bag of shite all for the sake of IJW... but why
you'd NEED existing code to compile managed I don't know.....
"Arnaud Debaene" <ad******@club-internet.fr> wrote in message
news:16**************************@posting.google.c om... "Ronald Laeremans [MSFT]" <ro*****@online.microsoft.com> wrote in message
news:<#Z**************@TK2MSFTNGP09.phx.gbl>... Yes.
Is there something more specific you are after?
Well, I must say I ran into a few problems with mixed MC++ / C++ when
you make heavy use of the RAII idiom : the .NET runtime seems to have
difficulties with tracking lifetime of parameters, which can have some
nasty side effects, even i f they are not related to GC.
See
http://groups.google.com/groups?hl=f....vc.language.* for the last dirty one.
Arnaud
MVP - VC
No.
"songie D" <so****@D.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl... Can managed C++ be trusted to handle the garbage collector correctly in
the right bit if I have a project with unmanaged and managed parts in it?
Songie, That's bollocks, there's no way you're supposed to change what's in the
contents of the system files. This isn't anything I've defined!
Who said you were supposed to change the contents of the system files? I
just said you should use a typedef in YOUR sourcecode referencing a .NET
CLASS to avoid having to always do the full-namespace+name thingie
everywhere which you complained about.
--
Tomas Restrepo to****@mvps.org
"songie D" <so****@D.com> wrote in message news:<em**************@TK2MSFTNGP09.phx.gbl>... ah, so you're a non-truster I see aswell :-)
I think I'll join you.
Writing software is not about trust, faith or believe, it is about
facts : I simply reported what I have observed, which has nothing to
do with GC, as I said.
It does all seem like a big bag of shite all for the sake of IJW...
Such childish reactions won't get you much attention here...
Arnaud
MVP - VC
Oh right, I see. But I don't see why I should have to if it's the
system files that have errored.
"Tomas Restrepo (MVP)" <to****@mvps.org> wrote in message
news:OJ**************@TK2MSFTNGP10.phx.gbl... Songie,
That's bollocks, there's no way you're supposed to change what's in the
contents of the system files. This isn't anything I've defined!
Who said you were supposed to change the contents of the system files? I
just said you should use a typedef in YOUR sourcecode referencing a .NET
CLASS to avoid having to always do the full-namespace+name thingie
everywhere which you complained about.
--
Tomas Restrepo
to****@mvps.org
"Arnaud Debaene" <ad******@club-internet.fr> wrote in message
news:16**************************@posting.google.c om... "songie D" <so****@D.com> wrote in message
news:<em**************@TK2MSFTNGP09.phx.gbl>... ah, so you're a non-truster I see aswell :-)
I think I'll join you.
Writing software is not about trust, faith or believe
Oh god, it is. I can't see all the people for who the only language they
will
ever know in their lives is VB6, making a decent living in 10 years time.
That's an answer that's the exact opposite of someone else's.
Strangely, it's you who I believe.
"MerkX Zyban" <Me***@NetWand.com> wrote in message
news:O4**************@TK2MSFTNGP11.phx.gbl... No.
"songie D" <so****@D.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl... Can managed C++ be trusted to handle the garbage collector correctly in
the right bit if I have a project with unmanaged and managed parts in it?
Yes, this is a know issue and one where (in contrast to the answer you got)
we do have different behavior for in Whidbey (i.e. the case you specifically
posted will work in Whidbey) although we are still looking for a solution
that will work in all cases. It doesn't specifically have to do with the
garbage collector which is the question I was trying to answer. (The issue
you posted the link to is a mostly a result of having different calling
conventions between managed and native code on X86.)
Ronald
"Arnaud Debaene" <ad******@club-internet.fr> wrote in message
news:16**************************@posting.google.c om... "Ronald Laeremans [MSFT]" <ro*****@online.microsoft.com> wrote in message
news:<#Z**************@TK2MSFTNGP09.phx.gbl>... Yes.
Is there something more specific you are after?
Well, I must say I ran into a few problems with mixed MC++ / C++ when
you make heavy use of the RAII idiom : the .NET runtime seems to have
difficulties with tracking lifetime of parameters, which can have some
nasty side effects, even i f they are not related to GC.
See
http://groups.google.com/groups?hl=f....vc.language.*
for the last dirty one.
Arnaud
MVP - VC
My best estimate is that the half life of any technical skill in this
industry is a few years at most. So anyone that does not gain new skills on
a constant basis throughput their career should really investigate their
choice of field to work in.
Ronald
"songie D" <so****@D.com> wrote in message
news:en**************@TK2MSFTNGP11.phx.gbl...
"Arnaud Debaene" <ad******@club-internet.fr> wrote in message
news:16**************************@posting.google.c om... "songie D" <so****@D.com> wrote in message
news:<em**************@TK2MSFTNGP09.phx.gbl>... > ah, so you're a non-truster I see aswell :-)
> I think I'll join you.
Writing software is not about trust, faith or believe
Oh god, it is. I can't see all the people for who the only language they
will
ever know in their lives is VB6, making a decent living in 10 years time.
On the basis of what facts?
Ronald
"songie D" <so****@D.com> wrote in message
news:Oo**************@TK2MSFTNGP09.phx.gbl... That's an answer that's the exact opposite of someone else's.
Strangely, it's you who I believe.
"MerkX Zyban" <Me***@NetWand.com> wrote in message
news:O4**************@TK2MSFTNGP11.phx.gbl... No.
"songie D" <so****@D.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl... > Can managed C++ be trusted to handle the garbage collector correctly in
the > right bit if I have a project with unmanaged and managed parts in it?
>
>
Ronald Laeremans [MSFT] wrote: Yes, this is a know issue and one where (in contrast to the answer
you got)
we do have different behavior for in Whidbey (i.e. the case you
specifically
posted will work in Whidbey) although we are still looking for a
solution
that will work in all cases. It doesn't specifically have to do with
the
garbage collector which is the question I was trying to answer. (The
issue
you posted the link to is a mostly a result of having different
calling
conventions between managed and native code on X86.)
Interesting, thanks. I have also posted a reference to my previous post in
the hope to gain a more complete answer from Microsoft :-)
Is there any KB or paper available on the subject? How can a calling
convention mismatch produce an abnormal call to a destructor? I hope it will
be fixed soon, since smart-ptr or the like (that is, RAII) is a very common
idiom in C++. For example, is it safe to use Alexandrescu's ScopeGuard
( http://www.cuj.com/documents/s=8000/...r/alexandr.htm) in an
MC++ environnement?
thanks again.
Arnaud
MVP - VC
It is not a calling convention mismatch. The calling convention is
different, so the CLR has to copy the arguments when going from native to
managed code.
There are 2 basic approaches, each with its sets of problems:
1) (What we do for 7.0 and 7.1). Have the CLR marshalling code try and call
copy constructors and destructors. The specific issue you saw is that the
copy constructor wasn't called from the user program so the linker threw the
code out and then the CLR tried to call the non existent version. For which
the workaround is to link with /opt:noref. A more insidious problem is that
the CLR marshalling code does not have enough information to call the copy
constructor and destructor in the right place which e.g. might lead to
double destruction.
2) (What we are doing for Whidbey Beta 1.) Have the CLR marshalling code
just do a bitwise copy. This will work correctly in all cases unless the
classes are self referential in some way (i.e. the take their own address or
the address of one of their members and store it away inside a member).
The second solution will work with the implementation of ScopeGuard as given
in the article.
Ronald Laeremans
Visual C++ team
"Arnaud Debaene" <ad******@club-internet.fr> wrote in message
news:ej****************@tk2msftngp13.phx.gbl... Ronald Laeremans [MSFT] wrote: Yes, this is a know issue and one where (in contrast to the answer
you got)
we do have different behavior for in Whidbey (i.e. the case you
specifically
posted will work in Whidbey) although we are still looking for a
solution
that will work in all cases. It doesn't specifically have to do with
the
garbage collector which is the question I was trying to answer. (The
issue
you posted the link to is a mostly a result of having different
calling
conventions between managed and native code on X86.)
Interesting, thanks. I have also posted a reference to my previous post in
the hope to gain a more complete answer from Microsoft :-)
Is there any KB or paper available on the subject? How can a calling
convention mismatch produce an abnormal call to a destructor? I hope it
will
be fixed soon, since smart-ptr or the like (that is, RAII) is a very
common
idiom in C++. For example, is it safe to use Alexandrescu's ScopeGuard
(http://www.cuj.com/documents/s=8000/...r/alexandr.htm) in
an
MC++ environnement?
thanks again.
Arnaud
MVP - VC
Songie, Oh right, I see. But I don't see why I should have to if it's the
system files that have errored.
Huh?
The system files are perfectly OK. It's not a problem, really, at all. It's
just a name clash, which could happen with any code.
Consider this perfectly valid C++ code:
namespace X {
class FILETIME {
};
}
using namespace X;
int main() {
FILETIME ft;
}
Now add #include <windows.h> on top of it and see what happens.
Let me reinstate it: IT IS NOT A BUG. It's just the way C++ works. You have
a type name that can be resolved to two different types within the same
scope. You need to explicitly tell the compiler which one it is you mean.
What's the big deal?
--
Tomas Restrepo to****@mvps.org This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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