[C++-sig] How to use BOOST_PYTHON_OPAQUE_SPECIALIZED_TYPE_ID ?

[Niall Douglas]

On 18 Sep 2008 at 5:21, William Marié wrote:

> I would need to create an opaque boost python type, i had a look on the
> internet, here is what i found for instance to declare a void* opaque type :
> 
> struct void_ {};
> BOOST_PYTHON_OPAQUE_SPECIALIZED_TYPE_ID(void_);

No, that's trickery from before my 2005 patch implementing native 
void * support.

> This works well if you have to call C++ function from Python but how do i do
> if i want to call a python function from C++ with a void* parameter :
> 
> ex :
> void* pFoo = 0x78985465;
> object callable = ....;
> callable( (void_*)pFoo );
> 
> I can't find out how to make this work properly i always have a runtime
> error :
> TypeError: No to_python (by-value) converter found for C++ type: struct
> void_ *

It just automatically works as an opaque pointer. Python cannot 
access the value, but can pass it into functions.

There should be an example in the regression suite.

Cheers,
Niall