python: expose pluginmanager.PluginMetadata.

doc/python/pages/changelog.rst

@@ -125,8 +125,9 @@ Changelog
 -   Exposed the :ref:`text` library
 -   Exposed the minimal interface of :ref:`utility.ConfigurationGroup` and
     :ref:`utility.Configuration`
--   Exposed :ref:`pluginmanager.AbstractManager.set_preferred_plugins()` and
+-   Exposed :ref:`pluginmanager.AbstractManager.set_preferred_plugins()`, the
-    the base :ref:`pluginmanager.AbstractPlugin` class
+    base :ref:`pluginmanager.AbstractPlugin` class and
+    :ref:`pluginmanager.PluginMetadata`
 -   Fixed issues with an in-source build (see :gh:`mosra/magnum-bindings#13`)
 -   All CMake build options are now prefixed with ``MAGNUM_``. For backwards
     compatibility, unless ``MAGNUM_BUILD_DEPRECATED`` is disabled and unless a

src/python/corrade/pluginmanager.cpp

@@ -31,6 +31,7 @@
 #include <Corrade/Containers/StringIterable.h>
 #include <Corrade/PluginManager/AbstractManager.h>
 #include <Corrade/PluginManager/AbstractPlugin.h>
+#include <Corrade/PluginManager/PluginMetadata.h>
 
 #include "Corrade/PythonBindings.h"
 
@@ -57,6 +58,12 @@ void pluginmanager(py::module_& m) {
         .value("USED", PluginManager::LoadState::Used);
     corrade::enumOperators(loadState);
 
+    py::class_<PluginManager::PluginMetadata>{m, "PluginMetadata", "Plugin metadata"}
+        .def_property_readonly("name", &PluginManager::PluginMetadata::name, "Plugin name")
+        .def_property_readonly("depends", &PluginManager::PluginMetadata::depends, "Plugins on which this plugin depends")
+        .def_property_readonly("used_by", &PluginManager::PluginMetadata::usedBy, "Plugins which depend on this plugin")
+        .def_property_readonly("provides", &PluginManager::PluginMetadata::provides, "Plugins which are provided by this plugin");
+
     PyNonDestructibleClass<PluginManager::AbstractManager> manager{m, "AbstractManager", "Base for plugin managers"};
     manager.attr("VERSION") = PluginManager::AbstractManager::Version;
     manager
@@ -99,7 +106,9 @@ void pluginmanager(py::module_& m) {
                 out.push_back(i);
             return out;
         }, "List of all available alias names")
-        /** @todo metadata() (figure out the ownership) */
+        .def("metadata", [](PluginManager::AbstractManager& self, const std::string& plugin) {
+            return self.metadata(plugin);
+        }, "Plugin metadata", py::arg("plugin"), py::return_value_policy::reference_internal)
         /** @todo drop std::string in favor of our own string caster */
         .def("load_state", [](PluginManager::AbstractManager& self, const std::string& plugin) {
             return self.loadState(plugin);
@@ -133,7 +142,8 @@ void pluginmanager(py::module_& m) {
         .def_property_readonly("plugin", [](PluginManager::AbstractPlugin& self) {
             /** @todo drop std::string in favor of our own string caster */
             return std::string{self.plugin()};
-        }, "Plugin identifier string");
+        }, "Plugin identifier string")
+        .def_property_readonly("metadata", &PluginManager::AbstractPlugin::metadata, "Plugin metadata", py::return_value_policy::reference_internal);
 }
 
 }

src/python/magnum/test/test_trade.py

@@ -1042,6 +1042,45 @@ class Importer(unittest.TestCase):
         with self.assertRaises(KeyError):
             manager.set_preferred_plugins('ApngImporter', [])
 
+    def test_metadata(self):
+        manager = trade.ImporterManager()
+        manager.set_preferred_plugins('PngImporter', ['StbImageImporter'])
+        manager_refcount = sys.getrefcount(manager)
+
+        metadata = manager.metadata('PngImporter')
+        self.assertEqual(sys.getrefcount(manager), manager_refcount + 1)
+        self.assertEqual(metadata.name, 'StbImageImporter')
+        self.assertEqual(metadata.provides, ['BmpImporter', 'GifImporter', 'HdrImporter', 'JpegImporter', 'PgmImporter', 'PicImporter', 'PngImporter', 'PpmImporter', 'PsdImporter', 'TgaImporter'])
+
+        del metadata
+        self.assertEqual(sys.getrefcount(manager), manager_refcount)
+
+        metadata = manager.metadata('GltfImporter')
+        self.assertEqual(sys.getrefcount(manager), manager_refcount + 1)
+        self.assertEqual(metadata.depends, ['AnyImageImporter'])
+
+        importer = manager.load_and_instantiate('GltfImporter')
+        importer_refcount = sys.getrefcount(importer)
+        self.assertEqual(sys.getrefcount(manager), manager_refcount + 2)
+
+        metadata = manager.metadata('AnyImageImporter')
+        # Replacing the previous metadata instance so it stays the same
+        self.assertEqual(sys.getrefcount(manager), manager_refcount + 2)
+        self.assertEqual(metadata.used_by, ['GltfImporter'])
+
+        # Retrieving metadata from the plugin instance should be the same
+        # instance
+        metadata_from_plugin = importer.metadata
+        self.assertEqual(sys.getrefcount(importer), importer_refcount + 1)
+        self.assertEqual(metadata_from_plugin.depends, ['AnyImageImporter'])
+
+        del metadata_from_plugin
+        self.assertEqual(sys.getrefcount(importer), importer_refcount)
+
+        del importer
+        del metadata
+        self.assertEqual(sys.getrefcount(manager), manager_refcount)
+
     def test_no_file_opened(self):
         importer = trade.ImporterManager().load_and_instantiate('StbImageImporter')
         self.assertFalse(importer.is_opened)