Just a small caveat/warning.
Interfaces across DLL boundaries are not type safe.
You have to get the type right for both the caller and callee.
This might get fixed later, it is not easy: we'd love to use C++
typesafe linkage but that means predicting mangled names.
We could also generate our own. In both cases there's a serious
problem that the names used in the caller C++ and the DLL C++
are actually distinct (because they involve different sequence numbers
generated by the compiler in two separate compilations).
There is a trick to getting the types right.
When you call into a DLL you're calling a C function generated by "export".
This function is given a type like:
export fun f of ( int * int ) as "f";
The type of this function is
ret f (int, int);
which is
int * int --> ret
in Felix. However you can NOT call this function with the type
indicated here:
f = Dynlink::func1[ret, int * int] (linst, "f");
All hell will break lose! You have to call it like this:
f = Dynlink::func2[ret, int, int] (linst, "f");
i.e. with two arguments, NOT with a single tuple argument.
It is certainly possible to pass tuples to C functions, but lacking
a "tuple of one type" there is no way to do this unless it is
one of several arguments: you can pass
int * ( int * int )
and the second argument is a tuple. You cannot pass a tuple to a C function
with a single argument, since Felix uses a "trick" to decode top level products
into
separate arguments (and there's no way to make a one argument tuple).
I fell into this trap. Be warned!
[Note: For ordinary C binding you CAN do it, there's a special code $t for
passing
all the arguments as a single tuple.]
--
john skaller
skal...@users.sourceforge.net
http://felix-lang.org
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