]>
Commit | Line | Data |
---|---|---|
7c673cae FG |
1 | [section boost/python/to_python_indirect.hpp] |
2 | [section Introduction] | |
3 | <boost/python/to_python_indirect.hpp> supplies a way to construct new Python objects that hold wrapped C++ class instances via a pointer or smart pointer. | |
4 | [endsect] | |
5 | [section Class `to_python_indirect`] | |
6 | Class template `to_python_indirect` converts objects of its first argument type to python as extension class instances, using the ownership policy provided by its 2nd argument. | |
7 | [table | |
8 | [[Parameter][Requirements][Description]] | |
9 | [[T][Either `U cv&` (where cv is any optional cv-qualification) or a [link concepts.dereferenceable Dereferenceable] type such that `*x` is convertible to `U const&`, where `U` is a class type. ][`A` type deferencing a C++ class exposed to Python using class template [link high_level_components.boost_python_class_hpp.class_template_class_t_bases_hel `class_`]. ]] | |
10 | [[MakeHolder][`h = MakeHolder::execute(p);` ][A class whose static `execute()` creates an `instance_holder`. ]] | |
11 | ] | |
12 | Instantiations of to_python_indirect are models of [link concepts.resultconverter `ResultConverter`]. | |
13 | `` | |
14 | namespace boost { namespace python | |
15 | { | |
16 | template <class T, class MakeHolder> | |
17 | struct to_python_indirect | |
18 | { | |
19 | static bool convertible(); | |
20 | PyObject* operator()(T ptr_or_reference) const; | |
21 | private: | |
22 | static PyTypeObject* type(); | |
23 | }; | |
24 | }} | |
25 | `` | |
26 | [endsect] | |
27 | [section Class `to_python_indirect` observers] | |
28 | ``PyObject* operator()(T x) const;`` | |
29 | [variablelist | |
30 | [[Requires][`x` refers to an object (if it is a pointer type, it is non-null). `convertible() == true`.]] | |
31 | [[Effects][Creates an appropriately-typed Boost.Python extension class instance, uses MakeHolder to create an instance_holder from x, installs the instance_holder in the new extension class instance, and returns a pointer to it.]] | |
32 | ] | |
33 | [endsect] | |
34 | [section Class `to_python_indirect` statics] | |
35 | ``bool convertible()`` | |
36 | [variablelist | |
37 | [[Effects][Returns true iff any module has registered a Python type corresponding to U. ]] | |
38 | ] | |
39 | [endsect] | |
40 | [endsect] | |
41 | [section Example] | |
42 | This example replicates the functionality of [link function_invocation_and_creation.models_of_resultconvertergenerat.boost_python_reference_existing_.class_reference_existing_object `reference_existing_object`], but without some of the compile-time error checking. | |
43 | `` | |
44 | struct make_reference_holder | |
45 | { | |
46 | typedef boost::python::objects::instance_holder* result_type; | |
47 | template <class T> | |
48 | static result_type execute(T* p) | |
49 | { | |
50 | return new boost::python::objects::pointer_holder<T*, T>(p); | |
51 | } | |
52 | }; | |
53 | ||
54 | struct reference_existing_object | |
55 | { | |
56 | // metafunction returning the ResultConverter | |
57 | template <class T> | |
58 | struct apply | |
59 | { | |
60 | typedef boost::python::to_python_indirect<T,make_reference_holder> type; | |
61 | }; | |
62 | }; | |
63 | `` | |
64 | [endsect] | |
65 | [endsect] |