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Implemented pure_virtual(...)
[SVN r19774]
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‎include/boost/python/detail/nullary_function_adaptor.hpp‎

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// Copyright David Abrahams 2003. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#ifndef NULLARY_FUNCTION_ADAPTOR_DWA2003824_HPP
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# define NULLARY_FUNCTION_ADAPTOR_DWA2003824_HPP
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namespace boost { namespace python { namespace detail {
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// nullary_function_adaptor -- a class template which ignores its
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// arguments and calls a nullary function instead. Used for building
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// error-reporting functions, c.f. pure_virtual
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template <class NullaryFunction>
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struct nullary_function_adaptor
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{
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nullary_function_adaptor(NullaryFunction fn)
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: m_fn(fn)
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{}
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void operator()() const { m_fn(); }
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# define BOOST_PP_LOCAL_MACRO(i) \
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template <BOOST_PP_ENUM_PARAMS_Z(1, i, class A)> \
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void operator()( \
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BOOST_PP_ENUM_BINARY_PARAMS_Z(1, i, A, const& BOOST_PP_INTERCEPT) \
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) const \
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{ \
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m_fn(); \
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}
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# define BOOST_PP_LOCAL_LIMITS (1, BOOST_PYTHON_MAX_ARITY)
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# include BOOST_PP_LOCAL_ITERATE()
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private:
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NullaryFunction m_fn;
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};
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}}} // namespace boost::python::detail
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#endif // NULLARY_FUNCTION_ADAPTOR_DWA2003824_HPP

‎include/boost/python/pure_virtual.hpp‎

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// Copyright David Abrahams 2003. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#ifndef PURE_VIRTUAL_DWA2003810_HPP
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# define PURE_VIRTUAL_DWA2003810_HPP
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# include <boost/python/def_visitor.hpp>
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# include <boost/python/default_call_policies.hpp>
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# include <boost/python/arg_from_python.hpp>
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# include <boost/mpl/push_front.hpp>
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# include <boost/mpl/pop_front.hpp>
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# include <boost/python/detail/nullary_function_adaptor.hpp>
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namespace boost { namespace python {
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namespace detail
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{
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//
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// { Helpers for pure_virtual_visitor, below.
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//
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// Raises a Python RuntimeError reporting that a pure virtual
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// function was called.
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void BOOST_PYTHON_DECL pure_virtual_called();
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// Replace the two front elements of S with T1 and T2
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template <class S, class T1, class T2>
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struct replace_front2
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{
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// Metafunction forwarding seemed to confound vc6
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typedef typename mpl::push_front<
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typename mpl::push_front<
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typename mpl::pop_front<
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typename mpl::pop_front<
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S
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>::type
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>::type
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, T2
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>::type
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, T1
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>::type type;
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};
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// Given an MPL sequence representing a signature, returns a new MPL
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// sequence whose return type is replaced by void, and whose first
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// argument is replaced by C&.
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template <class C, class S>
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typename replace_front2<S,void,C&>::type
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error_signature(S BOOST_APPEND_EXPLICIT_TEMPLATE_TYPE(C))
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{
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typedef typename replace_front2<S,void,C&>::type r;
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return r();
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}
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//
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// } Helpers for pure_virtual_visitor
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//
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//
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// A def_visitor which defines a method as usual, then adds a
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// corresponding function which raises a "pure virtual called"
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// exception unless it's been overridden.
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//
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template <class PointerToMemberFunction>
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struct pure_virtual_visitor
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: def_visitor<pure_virtual_visitor<PointerToMemberFunction> >
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{
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pure_virtual_visitor(PointerToMemberFunction pmf)
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: m_pmf(pmf)
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{}
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private:
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friend class def_visitor_access;
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template <class C_, class Options>
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void visit(C_& c, char const* name, Options& options) const
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{
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// This should probably be a nicer error message
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BOOST_STATIC_ASSERT(!Options::has_default_implementation);
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// Add the virtual function dispatcher
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c.def(
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name
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, m_pmf
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, options.doc()
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, options.keywords()
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, options.policies()
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);
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typedef BOOST_DEDUCED_TYPENAME C_::select_holder::held_type held_t;
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// Add the default implementation which raises the exception
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c.def(
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name
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, detail::make_function_aux(
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detail::nullary_function_adaptor<void(*)()>(pure_virtual_called)
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, default_call_policies()
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, args_from_python()
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, detail::error_signature<held_t>(detail::get_signature(m_pmf))
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)
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);
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}
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private: // data members
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PointerToMemberFunction m_pmf;
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};
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}
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//
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// Passed a pointer to member function, generates a def_visitor which
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// creates a method that only dispatches to Python if the function has
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// been overridden, either in C++ or in Python, raising a "pure
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// virtual called" exception otherwise.
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//
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template <class PointerToMemberFunction>
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detail::pure_virtual_visitor<PointerToMemberFunction>
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pure_virtual(PointerToMemberFunction pmf)
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{
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return detail::pure_virtual_visitor<PointerToMemberFunction>(pmf);
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}
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}} // namespace boost::python
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#endif // PURE_VIRTUAL_DWA2003810_HPP

‎src/object/function.cpp‎

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@@ -627,7 +627,7 @@ handle<> function_handle_impl(py_function const& f)
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new function(f, 0, 0)));
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}
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}
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} // namespace objects
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namespace detail
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{
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f
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, keyword_range(&k,&k));
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}
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void BOOST_PYTHON_DECL pure_virtual_called()
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{
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PyErr_SetString(PyExc_RuntimeError, "Pure virtual function called");
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throw_error_already_set();
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}
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}
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}} // namespace boost::python::objects
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}} // namespace boost::python

‎test/polymorphism.cpp‎

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@@ -9,6 +9,7 @@
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#include <boost/python/manage_new_object.hpp>
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#include <boost/python/reference_existing_object.hpp>
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#include <boost/python/call_method.hpp>
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#include <boost/python/pure_virtual.hpp>
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#include <boost/python/def.hpp>
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#include <boost/utility.hpp>
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PyObject* mSelf;
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};
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struct P
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{
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virtual ~P(){}
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virtual std::string f() = 0;
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};
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struct PCallback : P, Callback
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{
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PCallback (PyObject* self) : Callback(self) {}
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std::string f()
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{
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return call_method<std::string>(mSelf, "f");
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}
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};
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struct Q : P
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{
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std::string f() { return "Q::f()"; }
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};
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struct A
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{
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virtual ~A(){}
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struct B : A
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{
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virtual std::string f() { return "B::f()"; }
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virtual std::string f() { return "B::f()"; }
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};
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struct C : A
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def("factory", factory, return_value_policy<manage_new_object>());
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def("call_f", call_f);
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class_<P,boost::noncopyable,PCallback>("P")
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.def("f", pure_virtual(&P::f))
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;
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class_<Q, bases<P> >("Q")
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;
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}
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//#include "module_tail.cpp"

‎test/polymorphism.py‎

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@@ -46,7 +46,22 @@ def f(self):
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def test_wrapper_downcast(self):
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a = pass_a(D())
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self.failUnlessEqual('D::g()', a.g())
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def test_pure_virtual(self):
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p = P()
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self.assertRaises(RuntimeError, p.f)
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q = Q()
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self.failUnlessEqual ('Q::f()', q.f())
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class R(P):
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def f(self):
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return 'R.f'
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r = R()
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self.failUnlessEqual ('R.f', r.f())
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if __name__ == "__main__":
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# remove the option which upsets unittest

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