[C++-sig] shared_ptr converters

[David Abrahams]

Nicodemus <nicodemus at globalite.com.br> writes:

> David Abrahams wrote:
>
>>Nicodemus <nicodemus at globalite.com.br> writes:
>>  However, there is one significant difference: if you don't specify
>>shared_ptr<Y> then you will not be able to pass a Python X object as a
>>shared_ptr<Y>& argument.  Among other things that means you will not
>>be able to expose member functions of the shared_ptr as methods of the
>>wrapped X (see Raoul Gough's recent postings about proxies).  You will
>>still be able to pass a Python X object as shared_ptr<X>,
>>shared_ptr<Y>, shared_ptr<X> const&, or shared_ptr<Y> const&.
>>
>
> You mean that a function that receives a shared_ptr<X>& wouldn't work?
> Because the following does:
>
> int Test(boost::shared_ptr<A>& a)
> {
>     return a->f();
> }          >>> from test import *
>  >>> a = New()
>  >>> Test(a)
> 1
>
> Or am I misunderstood your response? 

Yes, my response was badly-phrased.  I should've said: if you don't
specify shared_ptr<X>, you won't be able to pass an X object
_constructed from Python_ to a function expecting shared_ptr<X>&:

             >>> a = A()
             >>> Test(a)
             Traceback...

> If the only drawback is not being
> able to expose member functions of the shared_ptr as methods of the
> wrapped object

And also not being able to detach the C++ object from the python
object:

  int Detach(boost::shared_ptr<A>& a)
  {
      a.reset();
  }

> I think it is acceptable for Pyste to do the more
> common thing, since this is a rare use case anyway. 8)

I agree.
-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com