[C++-sig] Exposing c++ class template to Python (known template instances)

[Holger Brandsmeier]

Dotan,

Well, you can derive your template class BarWithPolicy from a
non-template class IBarWithPolicy and maybe that interface is enough
to work with. Otherwise I usually drag the template arguments along on
the C++ side.

What exactly do you want to do with that object, that can then either
be a `BarWithPolicy<FooFilePolicy >` or `BarWithPolicy<FooIoPolicy >`?

-Holger

On Sun, Mar 17, 2013 at 1:50 PM, Dotan Barak <dbarak at gmail.com> wrote:
> Thanks for the response
>
> That trick can help me out in the python level since python is has a duck
> typing attribute.
>
> do you familiar with any a procedure for the C++ ?. what I mean is this : I
> would like to have some generic pointer that can either point to
> BarWithPolicy<FooFilePolicy > nor to BarWithPolicy<FooIoPolicy > ?
>
>
> thanks
> -Dotan
>
> On Sun, Mar 17, 2013 at 9:36 AM, Holger Brandsmeier <brandsmeier at gmx.de>
> wrote:
>>
>> Dotan,
>>
>> in
>>   >>> barPolicy = GetBarWithPolic(Io)
>>   >>> barPolicy = GetBarWithPolic(File)
>> what type of object would you imaginge `Io` and `File` to be?
>>
>> You already exported the functions as `GetBarWithPolicIo` and
>> `GetBarWithPolicFile` and then you could implement in python
>> `GetBarWithPolic(str)` and there use something like `return
>> globals()["GetBarWithPolic%s" % (str,)]()` where you would now do
>>   barPolicy = GetBarWithPolic("Io")
>>   barPolicy = GetBarWithPolic("File")
>>
>> -Holger
>>
>> On Sun, Mar 17, 2013 at 6:49 AM, dbarak <dbarak at gmail.com> wrote:
>> > Assume I have this Interface:
>> > class FooInterface
>> > {
>> > public:
>> >     ...
>> >
>> > };
>> >
>> > class FooFilePolicy : public FooInterface
>> > {
>> >  ...
>> > };
>> >
>> > class FooIoPolicy : public FooInterface
>> > {
>> >  ...
>> > };
>> >
>> > And I have this template using the upper interface policy:
>> >
>> > template< typename FooPolicy >
>> > class BarWithPolicy
>> > {
>> > ...
>> >     FooPolicy* policy;
>> > ...
>> > };
>> >
>> > How can I expose BarWithPolicy to python that can be generically
>> > instantiate
>> > with both  FooIoPolicy and FooFilePolicy ?
>> >
>> >
>> > I don't want to do this :
>> >
>> > BarWithPolicy<FooFilePolicy >& GetBarWithPolicyFile()
>> > {
>> >     return new BarWithPolicy<FooFilePolicy >;
>> > }
>> >
>> > BarWithPolicy<FooIoPolicy>& GetBarWithPolicyIo()
>> > {
>> >     return new BarWithPolicy<FooIoPolicy >;
>> > }
>> >
>> > BOOST_PYTHON_MODULE(PyBar)
>> > {
>> >     def("GetBarWithPolicyFile",
>> >         &GetBarWithPolicyFile,
>> >         return_value_policy<reference_existing_object>(),
>> >         ""
>> >         );
>> >     def("GetBarWithPolicyIo",
>> >         &GetBarWithPolicyIo,
>> >         return_value_policy<reference_existing_object>(),
>> >         ""
>> >         );
>> > }
>> >
>> > I would like to have some thing like this in python:
>> >
>> >>>> barPolicy = GetBarWithPolic(Io)
>> > Or
>> >>>> barPolicy = GetBarWithPolic(File)
>> >
>> > Thanks
>> > -Dotan
>> >
>> >
>> >
>> >
>> >
>> > --
>> > View this message in context:
>> > http://boost.2283326.n4.nabble.com/Exposing-c-class-template-to-Python-known-template-instances-tp4644238.html
>> > Sent from the Python - c++-sig mailing list archive at Nabble.com.
>> > _______________________________________________
>> > Cplusplus-sig mailing list
>> > Cplusplus-sig at python.org
>> > http://mail.python.org/mailman/listinfo/cplusplus-sig
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig at python.org
>> http://mail.python.org/mailman/listinfo/cplusplus-sig
>
>
>
>
> --
> Dotan Barak
>
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig at python.org
> http://mail.python.org/mailman/listinfo/cplusplus-sig