asyncio: Improve default writelines().

1 files changed, 12 insertions, 4 deletions

diff --git a/Lib/asyncio/transports.py b/Lib/asyncio/transports.py
index 86b850e..c2feb93 100644
--- a/Lib/asyncio/transports.py
+++ b/Lib/asyncio/transports.py
@@ -1,5 +1,9 @@
 """Abstract Transport class."""
 
+import sys
+
+PY34 = sys.version_info >= (3, 4)
+
 __all__ = ['ReadTransport', 'WriteTransport', 'Transport']
 
 
@@ -85,11 +89,15 @@ class WriteTransport(BaseTransport):
     def writelines(self, list_of_data):
         """Write a list (or any iterable) of data bytes to the transport.
 
-        The default implementation just calls write() for each item in
-        the list/iterable.
+        The default implementation concatenates the arguments and
+        calls write() on the result.
         """
-        for data in list_of_data:
-            self.write(data)
+        if not PY34:
+            # In Python 3.3, bytes.join() doesn't handle memoryview.
+            list_of_data = (
+                bytes(data) if isinstance(data, memoryview) else data
+                for data in list_of_data)
+        self.write(b''.join(list_of_data))
 
     def write_eof(self):
         """Close the write end after flushing buffered data.