Introduce finalizer module to manage finalization of C resources.

llvm/__init__.py

@@ -6,6 +6,8 @@ __version__ = '0.9.1'
 
 
 from weakref import WeakValueDictionary
+from llvm._utils.finalizer import track as track_resource
+from llvm._utils.finalizer import OwnerMixin as _OwnerMixin
 
 
 #===----------------------------------------------------------------------===
@@ -19,11 +21,26 @@ class LLVMException(Exception):
         Exception.__init__(self, msg)
 
 
+#===----------------------------------------------------------------------===
+# Resource Handle
+#===----------------------------------------------------------------------===
+
+class Handle(_OwnerMixin):
+    _finalizer = NotImplemented
+
+    def __init__(self, ptr):
+        self.ptr = ptr
+        self._finalizer_track(self.ptr)
+
+    @classmethod
+    def _finalize(cls, ptr):
+        cls._finalizer(ptr)
+
 #===----------------------------------------------------------------------===
 # Ownables
 #===----------------------------------------------------------------------===
 
-class Ownable(object):
+class Ownable(Handle):
     """Objects that can be owned.
 
     Modules and Module Providers can be owned, i.e., the responsibility of
@@ -32,25 +49,21 @@ class Ownable(object):
     is NOT intended for public use.
     """
 
-    def __init__(self, ptr, del_fn):
-        self.ptr = ptr
+    def __init__(self, ptr):
+        Handle.__init__(self, ptr)
         self.owner = None
-        self.del_fn = del_fn
 
     def _own(self, owner):
         if self.owner:
             raise LLVMException("object already owned")
         self.owner = owner
+        self._finalizer_untrack(self.ptr)
 
     def _disown(self):
         if not self.owner:
             raise LLVMException("not owned")
         self.owner = None
-
-    def __del__(self):
-        if not self.owner:
-            self.del_fn(self.ptr)
-
+        self._finalizer_track(self.ptr)
 
 #===----------------------------------------------------------------------===
 # Dummy owner, will not delete ownee. Be careful.