Stream_data streams data to a given output stream most efficiently with a low memory footprint.

Still, the git-cat-file command keeps all data in an interal buffer instead of streaming it directly.
This is a git design issue though, and will be hard to address without some proper git-hacking.

Conflicts:

	lib/git/cmd.py

Author: Byron

lib/git/cmd.py

@@ -183,7 +183,6 @@ def execute(self, command,
 								stdout=subprocess.PIPE,
 								**extra
 								)
-
 		if as_process:
 			return self.AutoInterrupt(proc)
 

lib/git/objects/base.py

@@ -127,6 +127,18 @@ def data_stream(self):
 		proc = self.repo.git.cat_file(self.type, self.id, as_process=True)
 		return utils.ProcessStreamAdapter(proc, "stdout") 
 
+	def stream_data(self, ostream):
+		"""
+		Writes our data directly to the given output stream
+		
+		``ostream``
+			File object compatible stream object.
+			
+		Returns
+			self
+		"""
+		self.repo.git.cat_file(self.type, self.id, output_stream=ostream)
+		return self
 
 class IndexObject(Object):
 	"""

test/git/test_base.py

@@ -4,12 +4,15 @@
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-from test.testlib import *
-from git import *
 import git.objects.base as base
 import git.refs as refs
+import os
+
+from test.testlib import *
+from git import *
 from itertools import chain
 from git.objects.utils import get_object_type_by_name
+import tempfile
 
 class TestBase(object):
 
@@ -53,6 +56,12 @@ def test_base_object(self):
 			data_stream = item.data_stream
 			data = data_stream.read()
 			assert data
+			
+			tmpfile = os.tmpfile()
+			assert item == item.stream_data(tmpfile)
+			tmpfile.seek(0)
+			assert tmpfile.read() == data
+			# END stream to file directly
 		# END for each object type to create
 
 		# each has a unique sha