[C++-sig] help on abstract class export

[Jakub Zytka]

On 04/29/11 09:14, zeb wrote:
> mb.free_fun('createWorker').call_policies =
> call_policies.return_value_policy(call_policies.return_pointee_value)
you do not want to have *value* of an abstract class.

> I found that if the IWorker class is not abstract, for example:
> class IWorker {
> public:
> 	virtual int getData() { return 0; }
> };
>
> Python doesn't report that error, but the result of the following code is
> not expected(I think it should be 100).
You expectancy is wrong. If you keep IWorker by value there will be no dynamic 
dispatch.
This is not related to py++, python or boost::python. Its just the same as in 
c++. If you wrote a c++ function that takes IWorker parameter by value you'd get 
the same behavior.

Basic rule of thumb: if you're dealing with inheritance, do not pass object by 
value.