P/Invoke marshalling

[ASB]

Bit long and rambly but here goes:-

I have a number of API's (about 300), they tend to use structures pretty much like this.

<StructLayout(LayoutKind.Sequential)> _
Friend Structure SomeReturnedData
Friend f1 As SomeField1
Friend f2 As SomeField2
Friend f3 As SomeField3
.....
.....
End Structure

<StructLayout(LayoutKind.Sequential)> _
Friend Structure SomeField1
Friend day As byte
Friend month As byte
Friend year As byte
End Structure

Now some field is the representation of a date at the other end (and there are a couple of hundred different types like this). Marshalling SomeReturnedData is not a problem, off it goes as a byte array and back it comes.

My problem arises when I want to do this:-

<StructLayout(LayoutKind.Sequential)> _
Friend Structure SomeField1
Friend day As byte
Friend month As byte
Friend year As byte

'Now some internal stuff which I don't want marshalled say:
Friend dt as DateTime

End Structure

The problem now of course is that the length changes from that expected. There is no <MarshalAs(IgnoreThisPlease)> type attribute.

Obviously I have to ensure that I ensure the integrity of the internal data structures after the structure has been marshalled - a nuisance but easily enough achievable (though not automatically of course since the constructor isn't run or anything).

Equally I can write wrappers for all the damn things, but what I want to do is encapsulate both the external and CLR representations in the structure.

Any suggestions as to how I can do that without resorting to a custom marshaller?

[Weltchy]

Any suggestions as to how I can do that without resorting to a custom marshaller?

None that spring to mind, sorry!!! Would be curious to see if anyone submits an answer tho, just out of professional curiosity!!!!

[DimPrawn]

Have you tried this free tool http://www.paulyao.com/resources/tools/pinvoke.asp

Anyway, you want Explicit not Sequential.

http://spellcoder.com/blogs/bashmoha...2/21/4654.aspx

I Think this will help.

[ASB]

DP,

The problem with the tools is I don't actually have any .H etc for the structure definitions. Only Cobol ones so I can't even avoid all the bleedin typing.

I want to avoid explicit and actually do this by applying pack:=1 to the structlayoutattribute. This ensures that the members are not reordered and contiguous.

But it does sound as though I am a bit stuffed and am going to have to produce a whole bunch of wrapper classes. Ah well.