DefaultValue and String in Managed C++

[Bram Vandendriesschen]

Hi,
anyone an idea how to get DefaultValue's working for
String properties in managed C++.
I wrote a component in managed C++ which I plan to consume
in C#. Now the IDE keeps inserting null-assignments for
the string properties, while I've specified that NULL is
the default value. Other types work well.

thanks in advance,
Bram.

[Mattias Sjögren]

Bram,

microsoft.public.dotnet.languages.vc is a better group for C++
questions.

Now the IDE keeps inserting null-assignments for
the string properties, while I've specified that NULL is
the default value. Other types work well.

Can you post your code?

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Bram Vanaelten]

Hi,
thanks for looking into my problem.
the code (managed C++) goes like this:

public __gc class SomeClass : public System::ComponentModel::Component
{
public:
SomeClass();
SomeClass(System::ComponentModel::IContainer container);
....
[DefaultValue(NULL)]
__property String* get_Kind();
[DefaultValue(NULL)]
__property String* set_Kind(String* value);
....
// other properties and methods
};

This class gets compiled into a component library. After dropping this
component on
a form (in C Sharp), the designer adds this line to the InitializeComponent
method of the form:

this.someClass1.Kind = null;

while I explicitly stated that that's the default value. BTW, it works as
expected with other types
like int, short, ...

I don't get it.
I am not using VS.NET 2003. It might be solved already (if it's a bug).

regards,
Bram.
"Mattias Sjögren" <ma********************@mvps.org> wrote in message
news:Ok**************@tk2msftngp13.phx.gbl...

Bram,

microsoft.public.dotnet.languages.vc is a better group for C++
questions.

Now the IDE keeps inserting null-assignments for
the string properties, while I've specified that NULL is
the default value. Other types work well.

Can you post your code?

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Mattias Sjögren]

Bram,

[DefaultValue(NULL)]

Since NULL is defined as 0, that compiles down to [DefaultValue(0)]
using the int constructor. And to managed code, 0 != null.

I tried some other possibilities, but wasn't able to get the same as
[DefaultValue(null)] does in C#. That's partly due to a compiler bug.

I suggest you re-post your problem to the VC newsgroup, where it's
more likely to be seen by people who know this stuff.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.