Re: [boost] [c++-sig]Python binding for templated constructor

Subject: Re: [boost] [c++-sig]Python binding for templated constructor
From: Sandeep Gupta (gupta.sandeep_at_[hidden])
Date: 2010-05-26 17:47:21

On Tue, May 25, 2010 at 9:23 PM, Jim Bosch <talljimbo_at_[hidden]> wrote:

> On 05/25/2010 01:58 PM, Sandeep Gupta wrote:
>
>> Hi,
>>  I have a class with a generic  constructor  as follows :
>> class X
>> {
>>   indexes m_idx;
>>   template<class strategy>
>>    X(){
>>      build_indexes<strategy>()
>> };
>>
>> My problem is that I am not able to figure out the syntax to export this
>> constructor. Is the above class not well  defined ?.
>>
>>
>>
>>
>
> That's a good question.  I'm not sure if it's possible using
> boost::python::init, but here's a possible workaround:
>
> namespace bp = boost::python;
>
> template <typename strategy>
> static X construct_X() { // could also return registered smart pointer to
> X.
>    return X<strategy>();
> }
>
> BOOST_PYTHON_MODULE(example) {
>    bp::class_<X>("X", bp::no_init)  // no_init keeps bp from trying to call
> default ctor
>        .def("__init__",
> bp::make_constructor(&construct_X<concrete_strategy>))
>        ;
> }
>
> I haven't tested that, but I think it should work.  By the way, you'll get
> more responses to Boost.Python questions at the Python/C++-sig mailing list:
>
> cplusplus-sig_at_[hidden]
>
>
> Hope that helps!
>
> Jim Bosch
>
>
Thanks Jim. For now I just added an extra function to the class X because it
was simpler.  I  didn't knew about no_init and make_constructor annotations.
Would try out the construct_X approach separately in due course. Thanks for
the tip to post to c++-sig mailing list as well.

Thanks.
-Sandeep