I'm trying to understand how to call a C++ library from D. Specifically,
the Windows Update API.

My goal is rather simple in that I want to detect whether there is a
reboot pending for the system. To do that I need to call the
ISystemInformation::RebootRequired property but I don't know how to do
that in D. Information about the call is at
http://msdn.microsoft.com/en-us/library/aa386098(v=vs.85).aspx.

I have the C++ header and have successfully defined VARIANT_BOOL,
VARIANT_TRUE, and VARIANT_FALSE. The last bit to do is to define the
ISystemInterface object itself and the RebootRequired method. How do I do
that?

-Dave

Unfortunately, you cant use C++ namespaces. More about interfacing to C++ here: http://www.dlang.org/cpp_interface.html .

The easiest way to solve this is to write a C function that will glue your code with the C++ library.

On Tuesday, 24 January 2012 at 12:30:26 UTC, David Eagen wrote:
> I'm trying to understand how to call a C++ library from D. Specifically,
> the Windows Update API.
>
> My goal is rather simple in that I want to detect whether there is a
> reboot pending for the system. To do that I need to call the
> ISystemInformation::RebootRequired property but I don't know how to do
> that in D. Information about the call is at
> http://msdn.microsoft.com/en-us/library/aa386098(v=vs.85).aspx.
>
> I have the C++ header and have successfully defined VARIANT_BOOL,
> VARIANT_TRUE, and VARIANT_FALSE. The last bit to do is to define the
> ISystemInterface object itself and the RebootRequired method. How do I do
> that?
>
> -Dave

From what I understand, the most reliable way currently is to wrap the C++ API in a C API and then call the C API from D. It's easy but time consuming and can't be generated currently.

I've never used the Windows update API, but isn't it a COM interface rather than a C++ interface? You can call those directly from D.

How about something like this (using Juno):

///////////////////////
import juno.com.core, std.stdio;

abstract final class SystemInformation {
  mixin(uuid("C01B9BA0-BEA7-41BA-B604-D0A36F469133"));
  mixin Interfaces!(ISystemInformation);
}

interface ISystemInformation : IDispatch
{
  mixin(uuid("ade87bf7-7b56-4275-8fab-b9b0e591844b"));

  int get_OemHardwareSupportLink(wchar* retval);
  int get_RebootRequired(out VARIANT_BOOL retval);
};

void main()
{
  //auto systemInformation =
coCreate!(ISystemInformation)(uuidof!(SystemInformation));
  auto systemInformation = SystemInformation.coCreate!ISystemInformation;

  if (systemInformation !is null)
  {
      scope(exit) tryRelease(systemInformation);

      VARIANT_BOOL b;
      int result = systemInformation.get_RebootRequired(b);

      if (SUCCEEDED(result))
      {
	  writefln("Reboot Required: %s", b);
      }
  }
}
///////////////////////

On Tue, 24 Jan 2012 07:22:46 -0600, Richard Webb <webby@beardmouse.org.uk> wrote:

> How about something like this (using Juno):
>
> ///////////////////////
> import juno.com.core, std.stdio;
>
> abstract final class SystemInformation {
>   mixin(uuid("C01B9BA0-BEA7-41BA-B604-D0A36F469133"));
>   mixin Interfaces!(ISystemInformation);
> }
>
> interface ISystemInformation : IDispatch
> {
>   mixin(uuid("ade87bf7-7b56-4275-8fab-b9b0e591844b"));
>
>   int get_OemHardwareSupportLink(wchar* retval);
>   int get_RebootRequired(out VARIANT_BOOL retval);
> };
>
> void main()
> {
>   //auto systemInformation =
> coCreate!(ISystemInformation)(uuidof!(SystemInformation));
>   auto systemInformation = SystemInformation.coCreate!ISystemInformation;
>
>   if (systemInformation !is null)
>   {
>       scope(exit) tryRelease(systemInformation);
>
>       VARIANT_BOOL b;
>       int result = systemInformation.get_RebootRequired(b);
>
>       if (SUCCEEDED(result))
>       {
> 	  writefln("Reboot Required: %s", b);
>       }
>   }
> }
> ///////////////////////

Thank you very much. This works great.

Yes, it turns out I was mistaken and this is COM and not C++. Juno definitely helps here. I cloned it from github and was glad to see that work had recently been done on Juno as well.

-Dave