Introduce utility function for deriving table fields

machines/power_storage.lua

@@ -15,8 +15,7 @@
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 local S=minetest.get_translator("industrialtest")
-industrialtest.PowerStorage=table.copy(industrialtest.ElectricMachine)
-industrialtest.internal.unpackTableInto(industrialtest.PowerStorage,{
+industrialtest.PowerStorage=industrialtest.internal.derive(industrialtest.ElectricMachine,{
 	facedir=true,
 	storageLists={
 		"charged",
@@ -63,8 +62,7 @@ function industrialtest.PowerStorage.getFormspec(self,pos)
 	return parentFormspec..table.concat(formspec,"")
 end
 
-industrialtest.BatBox=table.copy(industrialtest.PowerStorage)
-industrialtest.internal.unpackTableInto(industrialtest.BatBox,{
+industrialtest.BatBox=industrialtest.internal.derive(industrialtest.PowerStorage,{
 	name="industrialtest:batbox",
 	description=S("BatBox"),
 	tiles={
@@ -92,8 +90,7 @@ minetest.register_craft({
 	}
 })
 
-industrialtest.CESU=table.copy(industrialtest.PowerStorage)
-industrialtest.internal.unpackTableInto(industrialtest.CESU,{
+industrialtest.CESU=industrialtest.internal.derive(industrialtest.PowerStorage,{
 	name="industrialtest:cesu",
 	description=S("CESU"),
 	tiles={
@@ -121,8 +118,7 @@ minetest.register_craft({
 	}
 })
 
-industrialtest.MFE=table.copy(industrialtest.PowerStorage)
-industrialtest.internal.unpackTableInto(industrialtest.MFE,{
+industrialtest.MFE=industrialtest.internal.derive(industrialtest.PowerStorage,{
 	name="industrialtest:mfe",
 	description=S("MFE"),
 	tiles={
@@ -152,8 +148,7 @@ minetest.register_craft({
 })
 
 
-industrialtest.MFSU=table.copy(industrialtest.PowerStorage)
-industrialtest.internal.unpackTableInto(industrialtest.MFSU,{
+industrialtest.MFSU=industrialtest.internal.derive(industrialtest.PowerStorage,{
 	name="industrialtest:mfsu",
 	description=S("MFSU"),
 	tiles={