Failing to cast Project to VCProject (VS 2005 C# Addin)

[Luis Bascones]

Hello all.

Project specifics: Visual Studio 2005 C# Addin (under XP SP2)

I am having problems casting an project object from Project to VCProject. I
know it's a C++ project because I created a test one. When I try to cast it,
I get an E_NOINTERFACE exception with the following message:

"Unable to cast COM object of type 'System.__ComObject' to interface type
'Microsoft.VisualStudio.VCProjectEngine.VCProject'. This operation failed
because the QueryInterface call on the COM component for the interface with
IID '{238B5174-2429-11D7-8BF6-00B0D03DAA06}' failed due to the following
error: No such interface supported (Exception from HRESULT: 0x80004002
(E_NOINTERFACE))."

Thie code is structured so that there is delegate registered to handle the
OnOpened event:

// ********************************

public void OnConnection(object application, ext_ConnectMode connectMode,
object addInInst, ref Array custom)
{
_applicationObject = (DTE2)application;
_addInInstance = (AddIn)addInInst;

solutionEvents = _applicationObject.Events.SolutionEvents;
solutionEvents.Opened += new
_dispSolutionEvents_OpenedEventHandler(UpDateSolSettings);
}
// *********************************

The handler is supposed to modify attributes of all the VCProjects of the
solution:

// *********************************

private void UpDateSolSettings()
{
const string PROJECT_KIND_CPLUSPLUS_PROJECT =
"{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}";
VCConfiguration conf;
try
{
string strBaseDir = GetBaseDir();
if (null != strBaseDir)
{
foreach (Project proj in
_applicationObject.Solution.Projects)
{
if (proj.Kind == PROJECT_KIND_CPLUSPLUS_PROJECT)
{
VCProject vcproj = (VCProject)proj; //
<********* THE EXCEPTION IS THROWN HERE.
IVCCollection Confs =
(IVCCollection)vcproj.Configurations;
for (int iConf = 0, nConf = Confs.Count; iConf <
nConf; iConf++)
{
conf = (VCConfiguration)Confs.Item(iConf);
conf.IntermediateDirectory = strBaseDir +
@"\obj\win32\$(TargetName)";
}
}
}
}
}
catch(Exception e)
{
MessageBox.Show("Error: " + e.Message, "Error while
processing sol file.", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
}

// *********************************

Again, I am certain the solution only one project, and it's a VC++ project,
so the "proj" object should have the VCProject interface implemented.

Any ideas on what could be going on?

Any help greatly appreciated.

Regards,

Luis Bascones

[Carlos J. Quintero [VB MVP]]

Hi Luis,

You can not cast the variable proj from its type EnvDTE.Project to
VCProject. You must use the proj.Object property:

VCProject vcproj = (VCProject)proj.Object(); //

You can know the type behing a Object property as explained in my article:

HOWTO: Know the actual type behind a System.__ComObject type returned by an
.Object property.
http://www.mztools.com/resources_vsnet_addins.htm

--

Best regards,

Carlos J. Quintero

MZ-Tools: Productivity add-ins for Visual Studio
You can code, design and document much faster:
http://www.mztools.com

"Luis Bascones" <Luis.B...@mathworks.com> escribió en el mensaje
news:edPEVS1O...@TK2MSFTNGP03.phx.gbl...

[Luis Bascones]

Gracias Carlos,

Oh, I see. I guess the type I was casting from was just an interface type
and therefore I could not use it to QI for a another interface. I assume
that .Object returns IUnknown, which will allow me to QI for the interface I
am interested in (VCProject).

I will give that a shot. Hopefully it will make my code just work.

Gracias nuevamente,

-Luis Bascones

"Carlos J. Quintero [VB MVP]" <nos...@nospam.com> wrote in message
news:uqTJ$XjPHH...@TK2MSFTNGP05.phx.gbl...