refs now take repo as first argument and derive from LazyMixin to allow them to dynamically retrieve their objects

Improved way commits are returned by refs as they now use the path to be sure they always point to the ref even if it changes - previously it would use the sha intead so it would not update after being cached on the ref object

1 files changed, 25 insertions, 0 deletions

diff --git a/lib/git/utils.py b/lib/git/utils.py
index c204c432..39994bd5 100644
--- a/lib/git/utils.py
+++ b/lib/git/utils.py
@@ -24,3 +24,28 @@ def is_git_dir(d):
 				(os.path.islink(headref) and
 				os.readlink(headref).startswith('refs'))
 	return False
+	
+	
+class LazyMixin(object):
+	__slots__ = tuple()
+	
+	def __getattr__(self, attr):
+		"""
+		Whenever an attribute is requested that we do not know, we allow it 
+		to be created and set. Next time the same attribute is reqeusted, it is simply
+		returned from our dict/slots.
+		"""
+		self._set_cache_(attr)
+		# will raise in case the cache was not created
+		return object.__getattribute__(self, attr)
+
+	def _set_cache_(self, attr):
+		""" This method should be overridden in the derived class. 
+		It should check whether the attribute named by attr can be created
+		and cached. Do nothing if you do not know the attribute or call your subclass
+		
+		The derived class may create as many additional attributes as it deems 
+		necessary in case a git command returns more information than represented 
+		in the single attribute."""
+		pass
+