test_custom_type_casters.cpp

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/*
    tests/test_custom_type_casters.cpp -- tests type_caster<T>
 
    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
 
    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE file.
*/
 
#include "pybind11_tests.h"
#include "constructor_stats.h"
 
 
// py::arg/py::arg_v testing: these arguments just record their argument when invoked
class ArgInspector1 { public: std::string arg = "(default arg inspector 1)"; };
class ArgInspector2 { public: std::string arg = "(default arg inspector 2)"; };
class ArgAlwaysConverts { };
namespace pybind11 { namespace detail {
template <> struct type_caster<ArgInspector1> {
public:
    PYBIND11_TYPE_CASTER(ArgInspector1, _("ArgInspector1"));
 
    bool load(handle src, bool convert) {
        value.arg = "loading ArgInspector1 argument " +
            std::string(convert ? "WITH" : "WITHOUT") + " conversion allowed.  "
            "Argument value = " + (std::string) str(src);
        return true;
    }
 
    static handle cast(const ArgInspector1 &src, return_value_policy, handle) {
        return str(src.arg).release();
    }
};
template <> struct type_caster<ArgInspector2> {
public:
    PYBIND11_TYPE_CASTER(ArgInspector2, _("ArgInspector2"));
 
    bool load(handle src, bool convert) {
        value.arg = "loading ArgInspector2 argument " +
            std::string(convert ? "WITH" : "WITHOUT") + " conversion allowed.  "
            "Argument value = " + (std::string) str(src);
        return true;
    }
 
    static handle cast(const ArgInspector2 &src, return_value_policy, handle) {
        return str(src.arg).release();
    }
};
template <> struct type_caster<ArgAlwaysConverts> {
public:
    PYBIND11_TYPE_CASTER(ArgAlwaysConverts, _("ArgAlwaysConverts"));
 
    bool load(handle, bool convert) {
        return convert;
    }
 
    static handle cast(const ArgAlwaysConverts &, return_value_policy, handle) {
        return py::none().release();
    }
};
} // namespace detail
} // namespace pybind11
 
// test_custom_caster_destruction
class DestructionTester {
public:
    DestructionTester() { print_default_created(this); }
    ~DestructionTester() { print_destroyed(this); }
    DestructionTester(const DestructionTester &) { print_copy_created(this); }
    DestructionTester(DestructionTester &&) { print_move_created(this); }
    DestructionTester &operator=(const DestructionTester &) { print_copy_assigned(this); return *this; }
    DestructionTester &operator=(DestructionTester &&) { print_move_assigned(this); return *this; }
};
namespace pybind11 { namespace detail {
template <> struct type_caster<DestructionTester> {
    PYBIND11_TYPE_CASTER(DestructionTester, _("DestructionTester"));
    bool load(handle, bool) { return true; }
 
    static handle cast(const DestructionTester &, return_value_policy, handle) {
        return py::bool_(true).release();
    }
};
} // namespace detail
} // namespace pybind11
 
TEST_SUBMODULE(custom_type_casters, m) {
    // test_custom_type_casters
 
    // test_noconvert_args
    //
    // Test converting.  The ArgAlwaysConverts is just there to make the first no-conversion pass
    // fail so that our call always ends up happening via the second dispatch (the one that allows
    // some conversion).
    class ArgInspector {
    public:
        ArgInspector1 f(ArgInspector1 a, ArgAlwaysConverts) { return a; }
        std::string g(ArgInspector1 a, const ArgInspector1 &b, int c, ArgInspector2 *d, ArgAlwaysConverts) {
            return a.arg + "\n" + b.arg + "\n" + std::to_string(c) + "\n" + d->arg;
        }
        static ArgInspector2 h(ArgInspector2 a, ArgAlwaysConverts) { return a; }
    };
    // [workaround(intel)] ICC 20/21 breaks with py::arg().stuff, using py::arg{}.stuff works.
    py::class_<ArgInspector>(m, "ArgInspector")
        .def(py::init<>())
        .def("f", &ArgInspector::f, py::arg(), py::arg() = ArgAlwaysConverts())
        .def("g", &ArgInspector::g, "a"_a.noconvert(), "b"_a, "c"_a.noconvert()=13, "d"_a=ArgInspector2(), py::arg() = ArgAlwaysConverts())
        .def_static("h", &ArgInspector::h, py::arg{}.noconvert(), py::arg() = ArgAlwaysConverts())
        ;
    m.def("arg_inspect_func", [](ArgInspector2 a, ArgInspector1 b, ArgAlwaysConverts) { return a.arg + "\n" + b.arg; },
            py::arg{}.noconvert(false), py::arg_v(nullptr, ArgInspector1()).noconvert(true), py::arg() = ArgAlwaysConverts());
 
    m.def("floats_preferred", [](double f) { return 0.5 * f; }, "f"_a);
    m.def("floats_only", [](double f) { return 0.5 * f; }, "f"_a.noconvert());
    m.def("ints_preferred", [](int i) { return i / 2; }, "i"_a);
    m.def("ints_only", [](int i) { return i / 2; }, "i"_a.noconvert());
 
    // test_custom_caster_destruction
    // Test that `take_ownership` works on types with a custom type caster when given a pointer
 
    // default policy: don't take ownership:
    m.def("custom_caster_no_destroy", []() { static auto *dt = new DestructionTester(); return dt; });
 
    m.def("custom_caster_destroy", []() { return new DestructionTester(); },
            py::return_value_policy::take_ownership); // Takes ownership: destroy when finished
    m.def("custom_caster_destroy_const", []() -> const DestructionTester * { return new DestructionTester(); },
            py::return_value_policy::take_ownership); // Likewise (const doesn't inhibit destruction)
    m.def("destruction_tester_cstats", &ConstructorStats::get<DestructionTester>, py::return_value_policy::reference);
}