Interop assemblies containing certain constructs will cause a BadImageFormatException in .NET 4.0
Category Archives: COM
Beware of using stack-based COM objects from .NET
COM objects that don’t have the expected lifetime can cause chaos when combined with .NETs garbage collection system.
Getting IUnknown from __ComObject
How do you find the unmanaged COM object that’s being referenced by a .NET object?
Getting .NET type information in the unmanaged world
One of the tools that I write and maintain displays type information for COM objects hidden behind “handles” in Excel spreadsheets. The underlying objects can either support an interface that allows them to be richly rendered to XML, or the viewer will fall-back to using metadata and displaying the supported interfaces and their properties and methods. It [...]
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Beware cached IDispatch
I’ve kinda given it away there with the title, but we had an interesting set of symptoms exhibited the other day while trying to call a function in an Excel workbook via F#. It appeared that the function being called would fail depending on what had been called previously. Very odd.
A bit of background: as you [...]
Static libraries are Evil
In my opinion.
Why? Well, because it’s too easy to use them as an excuse for not defining your shared library interfaces properly.
The reason this is on my mind recently is that several hundred, yes, you heard that right, several hundred DLLs have been released by my group over the last, ooh, 10 years or so. [...]
F# – A little gotcha with GuidAttribute
Be careful when using the [<Guid("...")>] attribute on your COM-visible classes in F#. If you mistakenly use the curly-bracket delimited format for the GUID, regasm will silently, yes, silently, fail to add any CLSID entries for your class. That means it will be cocreatable by the prog ID, but not the CLSID. Ouch.
No doubt this will be [...]
Getting COM registration data with the activation context API
When moving code from “traditional” registry-based COM to shiny new side-by-side, registration-free COM, there are a few places where you might need an analog for things like looking up a DLL name from a prog ID. E.g. in the registry-based world, you can go from a Prog ID for a class to it’s physical DLL [...]
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Tracking COM memory using IMallocSpy
One of my aims at work is to simplify the development and testing regime as much as possible, and this mostly consists of making sure we’re using the most appropriate tools and technologies wherever possible. In the context of correctness checking this involves determining whether the time we spend installing, configuring and chasing down false [...]
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Bug in _com_ptr_t::QueryStdInterfaces
Just thought I’d bring people’s attention to a bug in the COM support classes that ship with Visual Studio 2005/VC8.
It’s a fairly unusual edge case (at least, if you’re not being passed VARIANTs from a script language), where the _variant_t helper class attempts to extract a standard COM interface (IUnknown or IDispatch) from a VARIANT [...]
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