[gentoo-commits] proj/R_overlay:master commit in: roverlay/util/

[André Erdmann]

commit:     758592e4107cae1a93c936062f0bda2bc9fc6dd5
Author:     André Erdmann <dywi <AT> mailerd <DOT> de>
AuthorDate: Thu Aug 29 12:24:54 2013 +0000
Commit:     André Erdmann <dywi <AT> mailerd <DOT> de>
CommitDate: Thu Aug 29 12:24:54 2013 +0000
URL:        http://git.overlays.gentoo.org/gitweb/?p=proj/R_overlay.git;a=commit;h=758592e4

roverlay/util/objects: more weak referencing

This functionality will (primarily) be used for handling distmap/mirror
directory file collisions.

---
 roverlay/util/objects.py | 154 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 135 insertions(+), 19 deletions(-)

diff --git a/roverlay/util/objects.py b/roverlay/util/objects.py
index 28cc4e8..ce4eccb 100644
--- a/roverlay/util/objects.py
+++ b/roverlay/util/objects.py
@@ -6,6 +6,85 @@
 
 import weakref
 
+class ObjectDisappeared ( Exception ):
+   pass
+# --- end of ObjectDisappeared ---
+
+class SafeWeakRef ( weakref.ref ):
+
+   def deref_unsafe ( self ):
+      return super ( SafeWeakRef, self ).__call__()
+   # --- end of deref_unsafe (...) ---
+
+   def deref_safe ( self ):
+      obj = super ( SafeWeakRef, self ).__call__()
+      if obj is not None:
+         return obj
+      else:
+         raise ObjectDisappeared()
+   # --- end of deref_safe (...) ---
+
+   __call__ = deref_safe
+   deref    = deref_safe
+
+   def __bool__ ( self ):
+      return self.deref_unsafe() is not None
+   # --- end of __bool__ (...) ---
+
+   def __repr__ ( self ):
+      obj = self.deref_unsafe()
+      if obj:
+         return "<{} at 0x{:x} to {!r} at 0x{:x}>".format (
+            self.__class__.__name__, id ( self ),
+            obj.__class__.__name__, id ( obj )
+         )
+      else:
+         return "<{} at 0x{:x} to None>".format (
+            self.__class__.__name__, id ( self )
+         )
+   # --- end of __repr__ (...) ---
+
+# --- end of SafeWeakRef ---
+
+
+class NoneRef ( object ):
+
+   def __init__ ( self, obj=None ):
+      super ( NoneRef, self ).__init__()
+      assert obj is None
+   # --- end of NoneRef (...) ---
+
+   def deref_unsafe ( self ):
+      return None
+   # --- end of deref_unsafe (...) ---
+
+   def deref_safe ( self ):
+      raise ObjectDisappeared()
+   # --- end of deref_safe (...) ---
+
+   __call__ = deref_safe
+   deref    = deref_safe
+
+   def __bool__ ( self ):
+      return False
+   # --- end of __bool__ (...) ---
+
+   def __repr__ ( self ):
+      return "<NoneRef at 0x{:x}>".format ( id ( self ) )
+   # --- end of __repr__ (...) ---
+
+# --- end of NoneRef ---
+
+def get_object_ref ( obj ):
+   if obj is None:
+      return NoneRef()
+   elif hasattr ( obj, 'get_ref' ):
+      return obj.get_ref()
+   else:
+      return SafeWeakRef ( obj )
+# --- end of get_object_ref (...) ---
+
+
 class MethodNotImplementedError ( NotImplementedError ):
    def __init__ ( self, obj, method, msg=None ):
       if isinstance ( obj, str ):
@@ -71,35 +150,72 @@ def not_implemented ( func=None ):
 # --- end of not_implemented (...) ---
 
 
+class Referenceable ( object ):
+
+   CACHE_REF = False
+
+   def __init__ ( self, *args, **kwargs ):
+      super ( Referenceable, self ).__init__()
+      self._cached_selfref = None
+      if self.CACHE_REF:
+         self.cache_ref()
+   # --- end of __init__ (...) ---
+
+   def cache_ref ( self ):
+      self._cached_selfref = self.get_new_ref()
+      self.get_ref = self._get_cached_ref
+   # --- end of cache_ref (...) ---
+
+   def _get_cached_ref ( self ):
+      return self._cached_selfref
+   # --- end of _get_cached_ref (...) ---
+
+   def get_new_ref ( self ):
+      return SafeWeakRef ( self )
+   # --- end of get_new_ref (...) ---
+
+   get_ref = get_new_ref
+
+# --- end of Referenceable ---
+
+
+class ReferenceTree ( Referenceable ):
+
+   def __init__ ( self, parent ):
+      super ( ReferenceTree, self ).__init__()
+      self.parent_ref = None
+      self.set_parent ( parent )
+   # --- end of __init__ (...) ---
+
+   def set_parent ( self, parent ):
+      self.parent_ref = get_object_ref ( parent )
+   # --- end of set_parent (...) ---
+
+   def get_parent ( self ):
+      return self.parent_ref.deref_safe()
+   # --- end of get_parent (...) ---
+
+   get_upper = get_parent
+
+# --- end of ReferenceTree ---
+
+
 class ObjectView ( object ):
 
-   class ObjectDisappeared ( Exception ):
-      pass
-   # --- end of ObjectDisappeared ---
+   ObjectDisappeared = ObjectDisappeared
 
    def __init__ ( self, obj ):
       super ( ObjectView, self ).__init__()
-      self.obj_ref = weakref.ref ( obj ) if obj is not None else None
+      self.obj_ref = get_object_ref ( obj )
+      self.deref_unsafe = self.obj_ref.deref_unsafe
+      self.deref_safe   = self.obj_ref.deref_safe
+      self.deref        = self.obj_ref.deref_safe
    # --- end of __init__ (...) ---
 
    def __bool__ ( self ):
-      return ( self.obj_ref is not None and self.obj_ref() is not None )
+      return bool ( self.obj_ref )
    # --- end of __bool__ (...) ---
 
-   def deref_unsafe ( self ):
-      return None if self.obj_ref is None else self.obj_ref()
-   # --- end of deref_unsafe (...) ---
-
-   def deref_safe ( self ):
-      obj = None if self.obj_ref is None else self.obj_ref()
-      if obj is None:
-         raise self.__class__.ObjectDisappeared()
-      else:
-         return obj
-   # --- end of deref_safe (...) ---
-
-   deref = deref_safe
-
    @abstractmethod
    def update ( self ):
       pass