pybind11/tests/test_kwargs_and_defaults.cpp

/*
    tests/test_kwargs_and_defaults.cpp -- keyword arguments and default values

    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 <pybind11/stl.h>

TEST_SUBMODULE(kwargs_and_defaults, m) {
    auto kw_func = [](int x, int y) { return "x=" + std::to_string(x) + ", y=" + std::to_string(y); };

    // test_named_arguments
    m.def("kw_func0", kw_func);
    m.def("kw_func1", kw_func, py::arg("x"), py::arg("y"));
    m.def("kw_func2", kw_func, py::arg("x") = 100, py::arg("y") = 200);
    m.def("kw_func3", [](const char *) { }, py::arg("data") = std::string("Hello world!"));

    /* A fancier default argument */
    std::vector<int> list{{13, 17}};
    m.def("kw_func4", [](const std::vector<int> &entries) {
        std::string ret = "{";
        for (int i : entries)
            ret += std::to_string(i) + " ";
        ret.back() = '}';
        return ret;
    }, py::arg("myList") = list);

    m.def("kw_func_udl", kw_func, "x"_a, "y"_a=300);
    m.def("kw_func_udl_z", kw_func, "x"_a, "y"_a=0);

    // test_args_and_kwargs
    m.def("args_function", [](py::args args) -> py::tuple { return args; });
    m.def("args_kwargs_function", [](py::args args, py::kwargs kwargs) {
        return py::make_tuple(args, kwargs);
    });

    // test_mixed_args_and_kwargs
    m.def("mixed_plus_args", [](int i, double j, py::args args) {
        return py::make_tuple(i, j, args);
    });
    m.def("mixed_plus_kwargs", [](int i, double j, py::kwargs kwargs) {
        return py::make_tuple(i, j, kwargs);
    });
    auto mixed_plus_both = [](int i, double j, py::args args, py::kwargs kwargs) {
        return py::make_tuple(i, j, args, kwargs);
    };
    m.def("mixed_plus_args_kwargs", mixed_plus_both);

    m.def("mixed_plus_args_kwargs_defaults", mixed_plus_both,
            py::arg("i") = 1, py::arg("j") = 3.14159);

    // pybind11 won't allow these to be bound: args and kwargs, if present, must be at the end.
    // Uncomment these to test that the static_assert is indeed working:
//    m.def("bad_args1", [](py::args, int) {});
//    m.def("bad_args2", [](py::kwargs, int) {});
//    m.def("bad_args3", [](py::kwargs, py::args) {});
//    m.def("bad_args4", [](py::args, int, py::kwargs) {});
//    m.def("bad_args5", [](py::args, py::kwargs, int) {});
//    m.def("bad_args6", [](py::args, py::args) {});
//    m.def("bad_args7", [](py::kwargs, py::kwargs) {});

    // test_function_signatures (along with most of the above)
    struct KWClass { void foo(int, float) {} };
    py::class_<KWClass>(m, "KWClass")
        .def("foo0", &KWClass::foo)
        .def("foo1", &KWClass::foo, "x"_a, "y"_a);
}