59 lines
1.5 KiB
Plaintext
59 lines
1.5 KiB
Plaintext
[section boost/python/copy_const_reference.hpp]
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[section Class `copy_const_reference`]
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`copy_const_reference` is a model of [link concepts.resultconverter.resultconvertergenerator_concept ResultConverterGenerator] which can be used to wrap C++ functions returning a reference-to-const type such that the referenced value is copied into a new Python object.
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``
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namespace boost { namespace python
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{
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struct copy_const_reference
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{
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template <class T> struct apply;
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};
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}}
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``
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[endsect]
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[section Class `copy_const_reference` metafunctions]
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``template <class T> struct apply``
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[variablelist
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[[Requires][`T` is `U const&` for some `U`.]]
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[[Returns][`typedef to_python_value<T> type;`]]
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]
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[endsect]
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[section Example]
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C++ module definition:
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``
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#include <boost/python/module.hpp>
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#include <boost/python/class.hpp>
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#include <boost/python/copy_const_reference.hpp>
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#include <boost/python/return_value_policy.hpp>
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// classes to wrap
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struct Bar { int x; }
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struct Foo {
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Foo(int x) : { b.x = x; }
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Bar const& get_bar() const { return b; }
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private:
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Bar b;
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};
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// Wrapper code
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using namespace boost::python;
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BOOST_PYTHON_MODULE(my_module)
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{
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class_<Bar>("Bar");
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class_<Foo>("Foo", init<int>())
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.def("get_bar", &Foo::get_bar
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, return_value_policy<copy_const_reference>())
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;
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}
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``
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Python code:
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``
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>>> from my_module import *
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>>> f = Foo(3) # create a Foo object
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>>> b = f.get_bar() # make a copy of the internal Bar object
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``
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[endsect]
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[endsect]
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