part: make blob optional on construction

Steve Canny · Steve Canny · commit d7c43e6266b7 · 2013-10-20T14:11:22.000-07:00
If sub-class decides to keep track of part content, by for example
transforming it into an ElementTree element and converting it back to
XML on blob() call, there is no need for Part base class to keep a
duplicate copy of the original content.
diff --git a/opc/package.py b/opc/package.py
@@ -97,7 +97,7 @@ class Part(object):
     intended to be subclassed in client code to implement specific part
     behaviors.
     """
-    def __init__(self, partname, content_type, blob):
+    def __init__(self, partname, content_type, blob=None):
         super(Part, self).__init__()
         self._partname = partname
         self._content_type = content_type
