python: add wrappers for often needed but terribly cryptic pybind APIs.

src/CMakeLists.txt

@@ -25,6 +25,7 @@
 
 set_directory_properties(PROPERTIES CORRADE_USE_PEDANTIC_FLAGS ON)
 
+add_subdirectory(Corrade)
 add_subdirectory(Magnum)
 
 if(WITH_PYTHON)

src/Corrade/CMakeLists.txt

@@ -0,0 +1,30 @@
+#
+#   This file is part of Magnum.
+#
+#   Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019
+#             Vladimír Vondruš <mosra@centrum.cz>
+#
+#   Permission is hereby granted, free of charge, to any person obtaining a
+#   copy of this software and associated documentation files (the "Software"),
+#   to deal in the Software without restriction, including without limitation
+#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
+#   and/or sell copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following conditions:
+#
+#   The above copyright notice and this permission notice shall be included
+#   in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+#   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+#   DEALINGS IN THE SOFTWARE.
+#
+
+if(WITH_PYTHON)
+    add_custom_target(CorradePython SOURCES Python.h)
+    set_target_properties(CorradePython PROPERTIES FOLDER "Corrade/Python")
+    install(FILES Python.h DESTINATION ${CORRADE_INCLUDE_INSTALL_DIR})
+endif()

src/Corrade/Python.h

@@ -0,0 +1,56 @@
+#ifndef Corrade_Python_h
+#define Corrade_Python_h
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019
+              Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include <pybind11/pybind11.h>
+#include <Corrade/Utility/Assert.h>
+
+namespace Corrade {
+
+template<class T> inline pybind11::handle pyHandleFromInstance(T& obj) {
+    /** @todo don't tell me there's no API for this either, ugh */
+    return pybind11::detail::get_object_handle(&obj, pybind11::detail::get_type_info(typeid(T)));
+}
+
+template<class T> inline pybind11::object pyObjectFromInstance(T& obj) {
+    /* reinterpret_borrow?! seriously?! */
+    return pybind11::reinterpret_borrow<pybind11::object>(pyHandleFromInstance(obj));
+}
+
+template<class T> inline T& pyInstanceFromHandle(pybind11::handle handle) {
+    /** @todo and this?! ugh! there's handle.cast() but that calls
+        caster.load(handle, true) which we DO NOT WANT */
+    /* Stolen from pybind11::class_::def_buffer(). Not sure what exactly it
+       does, but I assume caster is implicitly convertible to Class& and thus
+       can magically access the actual Class from the PyObject. */
+    pybind11::detail::make_caster<T> caster;
+    CORRADE_INTERNAL_ASSERT(caster.load(handle, /*convert=*/false));
+    return caster;
+}
+
+}
+
+#endif