Visual Studio Hacks

Access Visual Studio from Standalone Applications #87

Chapter 12, Extending Visual Studio

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387

HACK

It is a good idea to always use this method when accessing EnvDTE—while

you may have only one version of Visual Studio installed on your machine,

other users may have any number of versions installed.

The Notorious “Call Was Rejected by Callee” Error

While working with EnvDTE, you will most likely come across random occur-

rences of “Call was rejected by callee” errors. The key to avoiding this error

lies in using an OLE message filter. The filter will watch all calls, and when

one fails, it will wait and try again instead of throwing this error. The follow-

ing OLE message filter will watch for any calls and then retry them instead

of throwing an exception:

using System;

using System.Runtime.InteropServices;

class MessageFilter : IOleMessageFilter

{

//

// Public API

public static void Register( )

{

IOleMessageFilter newfilter = new MessageFilter( );

IOleMessageFilter oldfilter = null;

CoRegisterMessageFilter(newfilter, out oldfilter);

}

public static void Revoke( )

{

IOleMessageFilter oldfilter = null;

CoRegisterMessageFilter(null, out oldfilter);

}

//

// IOleMessageFilter impl

int IOleMessageFilter.HandleInComingCall(int dwCallType,

System.IntPtr hTaskCaller,

int dwTickCount,

System.IntPtr lpInterfaceInfo)

{

System.Diagnostics.Debug.WriteLine

("IOleMessageFilter::HandleInComingCall");

return 0; ...