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Managed C++ wrapper or DllImport?

Started by joanusdmentia Jun 5, 2004 at 7:27 PM 1 replies 2.3k views

Original Post

Jun 5, 2004 at 7:27 PM

I''m looking at using the recently released ODE 0.5 in a game being written in C#, however the provided .NET wrapper in the contrib/ dir don''t look like they''ve been updated to 0.5 so I''m going to write my own. Does anyone know whether there is any performance difference between writing managed C++ wrapper classes and compiling all of ODE into a managed assembly or just using the DllImport attribute in C# to call the functions in an unmanaged ODE dll? I''m currently leaning towards using DllImport since it would make things a bit more portable (as far as I know mono can''t handle mixed assemblies), but if the speed difference is enough then I''ll go with the C++ wrapper classes.

Arild Fines

Jun 5, 2004 at 7:50 PM

I''d think a Managed C++ solution would be slightly faster than P/Invoke. P/Invoke involves quite a bit of marshalling magic in some cases, and there is a reason why the general guideline is that P/Invoke calls should be few and chunky.

A mixed MC++ assembly shouldn''t require any marshalling.

(All of the above is just educated guesswork based on my knowledge of the technologies - I haven''t actually tested it.)

One thing, which may or may not be relevant in your case, is that mixed-mode MC++ assemblies won''t run under Mono or any other alternative .NET implementation, nor will they compile there unless someone develops an MC++ compiler for them. This is because mixed-mode assembles contain, by definition, unmanaged code, which is bound to the underlying platform.

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joanusdmentia

Jun 5, 2004 at 8:04 PM

quote:
Original post by Arild Fines
I''d think a Managed C++ solution would be slightly faster than P/Invoke. P/Invoke involves quite a bit of marshalling magic in some cases, and there is a reason why the general guideline is that P/Invoke calls should be few and chunky.

A mixed MC++ assembly shouldn''t require any marshalling.

That makes sense. Not really sure about MC++ assemblies not requiring marshalling though, I would have thought it would still be needed for passing objects between the managed and unmanaged C++ (I haven''t really done much with MC++ before, just C# as far as managed code goes).

quote:
Original post by Arild Fines
One thing, which may or may not be relevant in your case, is that mixed-mode MC++ assemblies won''t run under Mono or any other alternative .NET implementation, nor will they compile there unless someone develops an MC++ compiler for them. This is because mixed-mode assembles contain, by definition, unmanaged code, which is bound to the underlying platform.

This is as I thought and is the reason why I was leaning towards P/Invoke. Having said that though I won''t loose any sleep if it doesn''t end up being portable, it''s just something that would be ''nice'' to have the option of.

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