[PPL-devel] [Fwd: Re: Some troubles I met while building PPL.]

[Enea Zaffanella]

Yuriy Taraday <yorik.sar at gmail.com> wrote:
[...]
> By the way, in our project we use Java interface and we needed the value of
> PPL_Object.ptr to use in JNI library. May be, it should be somehow
> accessible from the outside? It might be useful for extending PPL and using
> it in conjunction with other libraries.

Well, I am a bit reluctant in making this publicly accessible, since it 
is an implementation detail and we would like to have maximum freedom 
about it (for instance, currently not all PPL Java objects are derived 
from PPL_Object).

Anyway, if you are working at the JNI level and you don't mind having to 
  fix your code whenever we might decide to change the implementation, 
then you should be able to extract the C++ pointer in the same way we 
currently do:

[code snippet from interfaces/Java/jni/ppl_java_globals.cc]
=================
   MIP_Problem* mip
     = reinterpret_cast<MIP_Problem*>(get_ptr(env, j_this_mip_problem));
=================

Here we use the helper function `get_ptr' function from 
ppl_java_common.defs.hh:

//! Returns a pointer to the C++ object wrapped by \p ppl_object.
void*
get_ptr(JNIEnv* env, const jobject& ppl_object);

to obtain a void*, which is then immediately cast to the appropriate C++ 
pointer type.

Regards,
Enea Zaffanella.