Topic: Why I get the null for AcadApplication?

[Andrey Bushman]

Code - C#: [Select]

1. // AutoCAD 2009 - 2013
2. using cad = Autodesk.AutoCAD.ApplicationServices.Application;
3. ...
4. Autodesk.AutoCAD.Interop.AcadApplication acadInt = cad.AcadApplication as Autodesk.AutoCAD.Interop.AcadApplication;
5.  

Why I get the null for acadInt variable on the some machines???

This code works fine in the AutoCAD 2009 (at our company), and in the AutoCAD 2010-2013 on virtual machines at my home. But it ain't working in the AutoCAD 2013 on machine at my office. Why???

I see it:

Code - C#: [Select]

1. Boolean x0 = cad.AcadApplication == null; // false
2. Boolean x1 = cad.AcadApplication is Autodesk.AutoCAD.Interop.AcadApplication; // false
3. Boolean x2 = cad.AcadApplication is Autodesk.AutoCAD.Interop.IAcadApplication; // false
4. Boolean x3 = cad.AcadApplication is Autodesk.AutoCAD.Interop._DAcadApplicationEvents_Event; // false
5.  

[TheMaster]

The same build will not work across all of those releases if it is referencing AutoCAD's COM interop assemblies (for which release?).

COM interop is release-dependent, and it isn't wise to be dependent on them, if you can avoid it.

You can use System.Dynamic in .NET 4.0 to make late-bound calls to AutoCAD COM methods without having to reference the COM assemblies.

[It's Alive!]

In theory, that call should never return null as I think the property calls acedGetIDispatch.  Unless of course the class AcadApplication has changed between versions as Tony mentioned.  Try a C style cast and see if you get a bad cast exception

[Andrey Bushman]

It is strangely: I removed this topic yesterday, because I found out a cause of error... But today I see it again and with answers.

All thanks for answers.

Earlier I compiled a code for AutoCAD 2009. I thought that if for assembly of Interop (the Autodesk.AutoCAD.Interop.Common.dll, and the Autodesk.AutoCAD.Interop.dll) "Copy Local"  is equal "false",  will be used the version  found in work process (x86/x64). My program worked in AutoCAD 2009 x86 and AutoCAD 2009 x64 without recompilation (I compiled as "AnyCPU"). But when I compiled it for AutoCAD 2012 and AutoCAD 2013 it ceased to work. If I specify for the Autodesk.AutoCAD.Interop.Common.dll, and for the Autodesk.AutoCAD.Interop.dll the exact versions of libraries (x86 or x64) then everything works fine.

But I still compile my program as "AnyCPU". Whether there can be problems because of it? Or it is better to me to recompile such programs as "x68" and "x64"?

Best Regards

[TheMaster]

In theory, that call should never return null as I think the property calls acedGetIDispatch.  Unless of course the class AcadApplication has changed between versions as Tony mentioned.  Try a C style cast and see if you get a bad cast exception

In the case of an RCW, using the 'as' operator leads to a call to IUnknown::QueryInterface() with the interface type specified in the [ComImport()] attribute on the RCW class. If it returns E_NOINTERFACE, 'as' doesn't throw any exception, it just returns null, so that is most-likely what's happening.