Support get/put for SGObject (#4066)

src/interfaces/swig/SGBase.i

@@ -525,3 +525,4 @@ copy_reg._reconstructor=_sg_reconstructor
 SUPPORT_TAG(String, string, std::string)
 SUPPORT_TAG(Float64, float, float64_t)
 SUPPORT_TAG(Int64, int, int64_t)
+SUPPORT_TAG(Object, object, CSGObject*)

src/shogun/base/SGObject.cpp

@@ -909,3 +909,17 @@ void CSGObject::list_observable_parameters()
 		    x.second.second.c_str());
 	}
 }
+
+bool CSGObject::has(const std::string& name) const
+{
+	return has_parameter(BaseTag(name));
+}
+
+void CSGObject::ref_value(CSGObject* const* value)
+{
+	SG_REF(*value);
+}
+
+void CSGObject::ref_value(...)
+{
+}

src/shogun/base/SGObject.h

@@ -300,10 +300,7 @@ class CSGObject
 	 * @param name name of the parameter
 	 * @return true if the parameter exists with the input name
 	 */
-	bool has(const std::string& name) const
-	{
-		return has_parameter(BaseTag(name));
-	}
+	bool has(const std::string& name) const;
 
 	/** Checks if object has a class parameter identified by a Tag.
 	 *
@@ -343,7 +340,10 @@ class CSGObject
 		if (has_parameter(_tag))
 		{
 			if(has<T>(_tag.name()))
+			{
+				ref_value(&value);
 				update_parameter(_tag, erase_type(value));
+			}
 			else
 			{
 				SG_ERROR("Type for parameter with name \"%s\" is not correct.\n",
@@ -552,6 +552,9 @@ class CSGObject
 	void unset_global_objects();
 	void init();
 
+	static void ref_value(CSGObject* const* value);
+	static void ref_value(...);
+
 	/** Checks if object has a parameter identified by a BaseTag.
 	 * This only checks for name and not type information.
 	 * See its usage in has() and has<T>().

src/shogun/base/class_list.h

@@ -46,6 +46,7 @@ namespace shogun {
 			delete object;
 			SG_SERROR("Type mismatch");
 		}
+		cast->ref();
 		return cast;
 	}
 }

tests/unit/base/MockObject.h

@@ -16,6 +16,11 @@ namespace shogun
 			init_params();
 		}
 
+		virtual ~CMockObject()
+		{
+			SG_UNREF(m_object);
+		}
+
 		const char* get_name() const
 		{
 			return "MockObject";
@@ -31,6 +36,11 @@ namespace shogun
 			return m_watched;
 		}
 
+		CSGObject* get_object() const
+		{
+			return m_object;
+		}
+
 	protected:
 		void init_params()
 		{
@@ -43,10 +53,17 @@ namespace shogun
 			    "watched_int", &m_watched,
 			    AnyParameterProperties(
 			        MS_NOT_AVAILABLE, GRADIENT_NOT_AVAILABLE));
+
+			watch_param(
+			    "watched_object", (CSGObject**)&m_object,
+			    AnyParameterProperties(
+			        MS_NOT_AVAILABLE, GRADIENT_NOT_AVAILABLE));
 		}
 
 	private:
 		int32_t m_integer = 0;
 		int32_t m_watched = 0;
+
+		CSGObject* m_object = 0;
 	};
 }

tests/unit/base/SGObject_unittest.cc

@@ -396,3 +396,16 @@ TEST(SGObject, watched_parameter)
 	EXPECT_EQ(obj->get<int32_t>("watched_int"), 12);
 	EXPECT_EQ(obj->get<int32_t>("watched_int"), obj->get_watched());
 }
+
+TEST(SGObject, watched_parameter_object)
+{
+	auto obj = some<CMockObject>();
+	Some<CMockObject> other_obj = some<CMockObject>();
+
+	EXPECT_EQ(other_obj->ref_count(), 1);
+	obj->put("watched_object", dynamic_cast<CSGObject*>(other_obj.get()));
+	EXPECT_EQ(other_obj->ref_count(), 2);
+	EXPECT_TRUE(other_obj->equals(obj));
+	obj = nullptr;
+	EXPECT_EQ(other_obj->ref_count(), 1);
+}