A Visual Basic COM object is simple to create, call and debug from Excel
At the SouthWest Fox conference in Phoenix I asked “How many people have Visual Studio?” Almost everybody raised their hand. Then I asked “How many people have used it?” Very few hands were raised. Here’s a simple way to create some VB.Net code and call it from VFP or Excel
Start Visual Studio.
Choose File->New->Project (VB Class Library)
Name VBCom
In Solution Explorer, Delete Class1.VB
Choose Project->Add Class->COM Class (you might have to scroll down to find “Com Class”) named ComClass1.VB
Add some code in the class definition just before the “End Class”:
Public function foobar(p1 as string) as string
Return p1 + “ VB was here”
Hit F9 to set a breakpoint on the Return statement
Hit F5. to build and execute. An error will occur:
A project with an Output Type of Class Library cannot be started directly.
In order to debug this project, go to the Debugging tab under Configuration Settings in Project Properties, and set the Start Action to Start External Program or Start URL. Alternatively, you can add a non-library project to this solution that uses a reference to this project and set it as the startup project.
Choose File->Add Project->Existing Project. Navigate to VFP9.EXE (typically in “c:\Program Files\Microsoft Visual Foxpro 9”)
Rt-Click on VFP9 in Solution Explorer. Choose “Set as startup project”
Rt-Click on VFP9 in Solution Explorer. Choose Properties->Debugger Type->Change from Auto to Managed Only
Hit F5. VFP starts up
Execute in VFP command window
x=CREATEOBJECT("vbcom.comclass1")
?x.foobar(“testparm”)
The breakpoint then hits in the debugger.
Instead of VFP, you can use Excel.
Choose Project->Add Existing Project. (It’s ok to have both VFP and Excel and Word, etc. in your solution.)
Navigate to Excel.Exe (typically in “c:\Program Files\Microsoft Office\Office11”)
When Excel starts, choose Tools->Macro->Visual Basic Editor.
When VB starts up, choose Insert->Module. Type
Sub Foo
MsgBox “test”
Hit the F5 button and see that the MessageBox fires.
Now choose Tools->References, add VBCom as a reference.
Add this code and hit F5
Set ox = CreateObject("vbcom.comclass1")
MsgBox ox.FooBar("Excel")
The breakpoint hits and Excel has called the VB Com object
If you’re feeling really adventurous, try using VFP and use this VB code:
Public Function FooBar(ByVal oVFP As Object) As VBCom.ComClass1
oVFP.DoCmd("Messagebox('Called via late binding')")
oVFP.GetType().InvokeMember("DoCmd", Reflection.BindingFlags.InvokeMethod, _
Nothing, oVFP, New Object() {"Messagebox('Called by Reflection')"})
Return Me
End Function
And call it with this VFP code:
x=CREATEOBJECT("vbcom.comclass1")
PUBLIC ox
ox=x.foobar(_vfp)
Anonymous
May 28, 2006
Hi,
How do I debug a class that is called from within a ASP.NET app?
Thanks,
chrisAnonymous
July 14, 2006
Here’s how you can use Visual Studio to create a .Net User Control that will act as an ActiveX control...Anonymous
July 20, 2006
It takes a lot of work to create the blog posts and code samples that I put in my blog, and I was curious...Anonymous
August 07, 2006
Here’s some C++ code to host the CLR. It’s an alternative to using COM Interop (see A Visual Basic COM...Anonymous
May 16, 2007
It’s simple to create a VFP object that can be used within other applications. I show how useful it isAnonymous
March 13, 2008
i need some code of visual basicAnonymous
May 08, 2008
I tried this using visual basic in vs2005 and excel 2003, but I get the error "File or assembly name vbcom, or one of its dependencies, was not found." Is this my error or just due to the fact that these are newer programs?Anonymous
May 28, 2008
How fast is interop code? If you’re in one kind of code and your calling another, what is the cost ofAnonymous
June 03, 2008
The comment has been removed