Re: [Chicken-users] easyffi c++ passing object pointers

[felix]

On Tue, 04 Nov 2003 21:07:50 -0500, Dave <address@hidden> wrote:

> Hello,
> How can I take pointers to objects that were created in C++, pass them 
> via an entry point, and manipulate them as tinyclos objects? Examples 
> exist for using c++ objects that are created by scheme and even pulling a 
> pointer from the tinyclos object, but I cannot figure out how to turn 
> this around. Here's one of my abortive attempts:
>
> #>!
> class ClientApp
> {
> public:
> bool ChickenCallin(char *helo);
>
> };
> <#
> ;;; INITIALIZE
> (define-entry-point 1
> ((a (pointer <ClientApp>)))
> (int)
> (print "Got client pointer")
> (print a)
> (print (ChickenCallin a "bing"))
> 1)

Argh. I didn't think of this. It's currently not really possible
to create a TinyCLOS instance from a C++ pointer. Thanks for pointing
this out! I have now implemented the following (slightly crude) method: the
initargs for the invocation of `make' can alternatively be the symbol 'this
followed by a pointer, so you would have something like this:

(define-entry-point 1 ((ptr c-pointer)) (int)
 (let ([a (make <ClientApp> 'this a)])
   (print (ChickenCallin a "bing"))
   1) )

Normally the initargs are passed to the C++ constructor. If 'this
is given, the C++ constructor will not be invoked.

I'll check this in the CVS in a few moments.


cheers,
felix