ExcelDNA / Managed XLL / Excel Interop

Question

I find it quite unbelieavble that the interop API is such a mess

A lot of methods have no comments on and seems to have been done very poorly

Has anyone else experienced the same and if so what library do you use to control Exel from C#?

Answer 1

The obvious practical problem with the VSTO/COM Interop technology is the overhead incurred when transitioning between worksheet and managed code. (And if you're trying to talk to Excel without the help of VSTO, stop doing so and save yourself some huge headaches). I thought VSTO did a pretty good job of providing a close analog of the Excel object model in the managed environment - certainly I didn't need to spend much time trying to understand much more about .NET Interop.

For longer-running automation activities the overhead's not so much of a problem, similar concerns to VBA automation apply: reduce calls across the interface as far as possible to get best performance.

For smaller, faster worksheet function-type work (the sort of thing where we might write an XLL, say) that overhead can be a killer. ExcelDNA seems to be a great way into delivering managed code through the XLL model - and the price is right.