refactor unpack, add unpack_from
diff --git a/Lib/struct.py b/Lib/struct.py
index ee5ddc2..648e39c 100644
--- a/Lib/struct.py
+++ b/Lib/struct.py
@@ -73,3 +73,15 @@
except KeyError:
o = _compile(fmt)
return o.unpack(s)
+
+def unpack_from(fmt, buf, offset=0):
+ """
+ Unpack the buffer, containing packed C structure data, according to
+ fmt starting at offset. Requires len(buffer[offset:]) >= calcsize(fmt).
+ See struct.__doc__ for more on format strings.
+ """
+ try:
+ o = _cache[fmt]
+ except KeyError:
+ o = _compile(fmt)
+ return o.unpack_from(buf, offset)
\ No newline at end of file