Add custom std::function<> caster.

tests/python/test_functional.cpp

@@ -0,0 +1,38 @@
+#include "pybind11_utils/functional.h"
+
+#include <pybind11/pybind11.h>
+
+PYBIND11_MODULE(functional, m)
+{
+    m.def("fn_0_arg", [](std::function<int()> const& fn) {
+        return fn();
+    });
+
+    m.def("fn_1_arg", [](std::function<int(int)> const& fn, int a) {
+        return fn(a);
+    });
+
+    m.def("fn_2_arg", [](std::function<int(int, int)> const& fn, int a, int b) {
+        return fn(a, b);
+    });
+
+    m.def("fn_0_or_1_arg", [](std::function<int()> const& fn) {
+        return fn();
+    });
+
+    m.def("fn_0_or_1_arg", [](std::function<int(int)> const& fn) {
+        return fn(1);
+    });
+
+    m.def("fn_1_or_2_or_3_arg", [](std::function<int(int)> const& fn) {
+        return fn(1);
+    });
+
+    m.def("fn_1_or_2_or_3_arg", [](std::function<int(int, int)> const& fn) {
+        return fn(1, 2);
+    });
+
+    m.def("fn_1_or_2_or_3_arg", [](std::function<int(int, int, int)> const& fn) {
+        return fn(1, 2, 3);
+    });
+}

tests/python/test_functional.py

@@ -0,0 +1,43 @@
+import mobase
+import pytest
+
+m = pytest.importorskip("mobase_tests.functional")
+
+
+def test_guessed_string():
+
+    # available functions:
+    # - fn_0_arg, fn_1_arg, fn_2_arg
+    # - fn_0_or_1_arg, fn_1_or_2_or_3_arg
+
+    assert m.fn_0_arg(lambda: 0) == 0
+    assert m.fn_0_arg(lambda: 5) == 5
+    assert m.fn_0_arg(lambda x=2: x) == 2
+    assert m.fn_0_arg(lambda *args: len(args)) == 0
+
+    assert m.fn_1_arg(lambda x: x, 4) == 4
+    assert m.fn_1_arg(lambda *args: sum(args), 8) == 8
+    assert m.fn_1_arg(lambda x=2, y=4: x + y, 3) == 7
+    assert m.fn_1_arg(lambda x, *args, **kwargs: x + len(args), 5) == 5
+
+    assert m.fn_2_arg(lambda x, y: x * y, 4, 5) == 20
+    assert m.fn_2_arg(lambda x, y=3: x * y, 4, 2) == 8
+    assert m.fn_2_arg(lambda *args: sum(args), 8, 9) == 17
+    assert m.fn_2_arg(lambda x=2, y=4: x + y, 3, 3) == 6
+    assert m.fn_2_arg(lambda x, *args, **kwargs: x + len(args), 5, 2) == 6
+
+    assert m.fn_0_or_1_arg(lambda: 3) == 3
+    assert m.fn_0_or_1_arg(lambda x: x) == 1
+
+    # the 0 arg is bound first, both are possible, the 0 arg is chosen
+    assert m.fn_0_or_1_arg(lambda x=2: x) == 2
+
+    with pytest.raises(TypeError):
+        m.fn_1_or_2_or_3_arg(lambda: 0)
+
+    assert m.fn_1_or_2_or_3_arg(lambda x=4: x) == 1
+    assert m.fn_1_or_2_or_3_arg(lambda x, y: x + y) == 3  # 1 + 2
+    assert m.fn_1_or_2_or_3_arg(lambda x, y, z: x * y * z) == 6  # 1 * 2 * 3
+
+    # the 1 arg is bound first
+    assert m.fn_1_or_2_or_3_arg(lambda *args: sum(args)) == 1