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Crashes using F# type instances in C# Office Add-in
f#c#

I have an F# library which I want to use with a Word 2007 add-in written in C#. In the add-in's ribbon button handler, I (naively, no doubt) create an instance of an F# type and invoke one of its member functions. Walking through the code with the VS debugger, the instance appears to be created without a problem, and the member function invocation (which in turn invokes a local, static F# function at the top level) seems to go just fine until the F# code hits the first "let" binding in the static function. Stepping into the "let" binding causes the add-in to crash (shutting down the Word instance that was started by the debugger) without an error message. Bracketing the offending code with an exception handler does nothing, regardless of whether the handling is implemented in the F# code or in the calling C# routine.

I can provide the code listing if needed, but I wanted to check first if there was something obvious and generic that I was missing.

Thanks!

.

Solved! My naivete has served me well, in spite of the fact that my F# newbieness has not. It seems that my constructed type had some glitches, in spite of the fact that it seemed to compile just fine. Apparently, the "constructor" part of the type has problems with "naked" imperative statements (i.e., statements not preceded by a "do" keyword) such as the following:

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type RequirementsDocument(doc : Microsoft.Office.Interop.Word.Document) =
	let mutable theDocument = doc
	let mutable theMainDocument = doc.Content
	doc.add_ContentControlOnEnter(new DocumentEvents2_ContentControlOnEnterEventHandler(fun cc -> (ContentControlEnter cc)))
	doc.add_ContentControlOnExit(new DocumentEvents2_ContentControlOnExitEventHandler(fun cc cancel -> (ContentControlExit cc cancel)))

Changing this to the following seems to have done the trick:

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type RequirementsDocument(doc : Microsoft.Office.Interop.Word.Document) =
	let mutable theDocument = doc
	let mutable theMainDocument = doc.Content
	do doc.add_ContentControlOnEnter(new DocumentEvents2_ContentControlOnEnterEventHandler(fun cc -> (ContentControlEnter cc)))
	do doc.add_ContentControlOnExit(new DocumentEvents2_ContentControlOnExitEventHandler(fun cc cancel -> (ContentControlExit cc cancel)))

Can anyone shed some light on why this change fixed the problem, and why the original code wasn't flagged by the compiler?

Thanks

By on 5/30/2008 10:20 AM ()

Hi there,

If you get a chance to post the original code to "fsbugs" at microsoft then please do so.

Kind regards

Don

By on 6/7/2008 11:41 PM ()

Hi Don,

I just sent it off.

Keep up the good work, by the way!

Cheers,
Fred

By on 6/8/2008 9:33 AM ()

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