Re: Can't seem to get abstract to work in unmanaged class

From:
"Bo Persson" <bop@gmb.dk>
Newsgroups:
microsoft.public.vc.language
Date:
Fri, 25 Aug 2006 17:24:19 +0200
Message-ID:
<4l8j10FovbiU1@individual.net>
"Alex Blekhman" <xfkt@oohay.moc> skrev i meddelandet
news:OawQE6EyGHA.3400@TK2MSFTNGP05.phx.gbl...

"nickdu" <nickdu@discussions.microsoft.com> wrote in message
news:3A4FA5AD-52EE-4BB8-B83E-2324F6D8C73C@microsoft.com...

I want to define something like an interface, however I want one of
the
methods to make use of a variable number of arguments and since an
interface
won't let me do that I figured an abstract class would be the next
best
thing. After reading
http://msdn2.microsoft.com/en-us/library/z8ew2153.aspx
I assumed I would be able to define this unmanaged C++ abstract
class in
VS.NET 2003. However when I compile with the class defined as:

#pragma once

#include <stdarg.h>

class ILogger abstract
{
public:
virtual void Log(short type, long severityLevel, const char
*format, ...) =
0;
virtual void LogArg(short type, long severityLevel, const char
*format,
va_list argList) = 0;
};

I get the following error:

...
c:\data\development\interface\logger.h(6) : error C2470: 'abstract'
: looks
like
a function definition, but there is no formal parameter list;
skipping
apparent
body
...

If I remove 'abstract' it compiles fine.

What am I doing wrong?


`abstract' keyword is VS2005 feature (C++/CLI, to be exact). I'm not
sure it's available in VS2003.NET.


It's is not needed in ISO C++ ("real C++"). Just define your pure
virtual functions, and the class is abstract.

On the other hand, variable number of arguments looks so very C. How
many variants do you expect? Could it be handled in a type safe manner
with a few overloads, or a template?

Bo Persson

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