Re: Storing C++ data in an instance field using CNI?

[Dalibor Topic <robilad at kaffe dot org>]

Andrew Haley wrote:
> David Daney writes:
>  > Paul Gear wrote:
>  > 
>  > >Hi folks,
>  > >
>  > >I've searched the archives & Google without finding an answer to this
>  > >question: is it possible using CNI to store C++ data in the object as an
>  > >instance field?
>  > >
>  > >I need to store a struct defined in an external library within the
>  > >object.  Can i just define a field that is of type Object and then use
>  > >that as a pointer?  If i do this, do i need to use special malloc/free
>  > >routines?
>  > >
>  > >Thanks in advance,
>  > >Paul
>  > >http://paulgear.webhop.net
>  > >  
>  > >
>  > I think the traditional way to do it with JNI and CNI is to define an 
>  > int (or long if using 64 bit pointers) member in the java object that 
>  > will be casted to a pointer to the C++ data object.
>
> Please, if you're going to use an integral type, use a long.  I once
> spent more than a month converting a huge code base that used ints to
> store pointers.
>
> The other thing you can do if using an integral type, is:
>
> foo bar (int /*PTR*/ first, int /*PTR*/ second)
>
> and you can then mechanically convert from one to t'other with a
> trivial script.

wouldn't a

typedef long native_ptr;

be much better? Then you'd need to change it in a single place.

cheers,
dalibor topic