[Ironruby-core] Leveraging StdLib.Win32API class

[James Leskovar]

Hi Tomas,

I've been playing around with DynamicMethod and generating IL at 
runtime, with varying levels of success. Currently I'm using 
DynamicMethod to generate the IL to load arguments, load function 
address, calli and ret. My script gets access to the DynamicMethod 
object, which gets passed onto a helper CLR method along with arguments 
for some basic marshalling, before being passed onto 
DynamicMethod.Invoke.

I've noticed though that calling .Invoke() in this manner is a magnitude 
times slower than using the equivalant Win32API code. I figure I'm meant 
to use CreateDelegate instead of Invoke, though I'm not sure how this is 
meant to work since CreateDelegate expects a delegate type, whose 
signature isn't known until runtime.

Regards,
James

Tomas Matousek wrote:
> I wouldn't recommend using Win32API. It's not well designed interop 
> library.
> 
> What you need is calli IL instruction. It takes a pointer to a function 
> and arguments and calls the function. C# doesn't support this so you 
> need some helpers. You can either emit them at run-time and call them 
> via delegates (that's what our implementation of Win32API does), or you 
> can write them in IL, if you know the signatures you need, compile them 
> to an assembly (ilasm ILHelpers.il /dll /out=ILHelpers.dll) and use the 
> assembly directly from Ruby (see attached file).
> 
> Tomas

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