demos enhanced during workshop at Garoa

concurrency/tcp_charserver.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+import sys
 import asyncio
 
 from charfinder import UnicodeNameIndex
@@ -13,8 +14,8 @@ index = None  # a UnicodeNameIndex instance
 @asyncio.coroutine
 def handle_queries(reader, writer):
     while True:
-        writer.write(PROMPT)
-        yield from writer.drain()
+        writer.write(PROMPT)  # can't yield from!
+        yield from writer.drain()  # must yield from!
         data = yield from reader.readline()
         try:
             query = data.decode().strip()
@@ -29,15 +30,18 @@ def handle_queries(reader, writer):
             if lines:
                 writer.writelines(line.encode() + CRLF for line in lines)
             writer.write(index.status(query, len(lines)).encode() + CRLF)
+    
             yield from writer.drain()
+            print('Sent {} results'.format(len(lines)))
 
     print('Close the client socket')
     writer.close()
 
 
-def main():
+def main(address='127.0.0.1', port=8888):
+    port = int(port)
     loop = asyncio.get_event_loop()
-    coro = asyncio.start_server(handle_queries, '127.0.0.1', 8888, loop=loop)
+    coro = asyncio.start_server(handle_queries, address, port, loop=loop)
     server = loop.run_until_complete(coro)
 
     host = server.sockets[0].getsockname()
@@ -54,4 +58,4 @@ def main():
 
 if __name__ == '__main__':
     index = UnicodeNameIndex()
-    main()
+    main(*sys.argv[1:])