Object type with constructors and destructorsHEADmaster

1 files changed, 42 insertions, 0 deletions

diff --git a/src/Script/Object.hs b/src/Script/Object.hs
new file mode 100644
index 0000000..9232b21
--- /dev/null
+++ b/src/Script/Object.hs
@@ -0,0 +1,42 @@
+module Script.Object (
+    ObjectId(..),
+    ObjectType(..),
+    Object(..), SomeObject(..),
+    toSomeObject, fromSomeObject,
+    destroySomeObject,
+) where
+
+import Data.Kind
+import Data.Typeable
+
+
+newtype ObjectId = ObjectId Int
+
+class Typeable a => ObjectType m a where
+    type ConstructorArgs a :: Type
+    type ConstructorArgs a = ()
+
+    createObject :: ObjectId -> ConstructorArgs a -> m (Object m a)
+    destroyObject :: Object m a -> m ()
+
+data Object m a = ObjectType m a => Object
+    { objId :: ObjectId
+    , objImpl :: a
+    }
+
+data SomeObject m = forall a. ObjectType m a => SomeObject
+    { sobjId :: ObjectId
+    , sobjImpl :: a
+    }
+
+toSomeObject :: Object m a -> SomeObject m
+toSomeObject Object {..} = SomeObject { sobjId = objId, sobjImpl = objImpl }
+
+fromSomeObject :: ObjectType m a => SomeObject m -> Maybe (Object m a)
+fromSomeObject SomeObject {..} = do
+    let objId = sobjId
+    objImpl <- cast sobjImpl
+    return Object {..}
+
+destroySomeObject :: SomeObject m -> m ()
+destroySomeObject (SomeObject oid impl) = destroyObject (Object oid impl)