dynamic attributes, descriptors and first concurrency examples

concurrency/tcp_charserver.py

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+#!/usr/bin/env python3
+
+import asyncio
+
+from charfinder import UnicodeNameIndex
+
+CRLF = b'\r\n'
+PROMPT = b'?> '
+
+index = None  # a UnicodeNameIndex instance
+
+
+def writeln(writer, arg):
+    if isinstance(arg, str):
+        lines = [arg]
+    else:
+        lines = arg
+    writer.writelines(line.encode() + CRLF for line in lines)
+
+
+@asyncio.coroutine
+def handle_queries(reader, writer):
+    while True:
+        writer.write(PROMPT)
+        yield from writer.drain()
+        data = yield from reader.readline()
+        try:
+            query = data.decode().strip()
+        except UnicodeDecodeError:
+            query = '\x00'
+        if ord(query[:1]) < 32:
+            break
+        client = writer.get_extra_info('peername')
+        print('Received from {}: {}'.format(client, query))
+        lines = list(index.find_descriptions(query))
+        if lines:
+            writeln(writer, lines)
+            plural = 'es' if len(lines) > 1 else ''
+            msg = '({} match{} for {!r})'.format(len(lines), plural, query)
+            writeln(writer, msg)
+            print('Sent: {} lines + total'.format(len(lines)))
+        else:
+            writeln(writer, '(No match for {!r})'.format(query))
+            print('Sent: 1 line, no match')
+        yield from writer.drain()
+
+    print('Close the client socket')
+    writer.close()
+
+
+def main():
+    loop = asyncio.get_event_loop()
+    coro = asyncio.start_server(handle_queries, '127.0.0.1', 8888, loop=loop)
+    server = loop.run_until_complete(coro)
+
+    host = server.sockets[0].getsockname()
+    print('Serving on {}. Hit CTRL-C to stop.'.format(host))
+    try:
+        loop.run_forever()
+    except KeyboardInterrupt:  # CTRL+C pressed
+        pass
+
+    server.close()
+    loop.run_until_complete(server.wait_closed())
+    loop.close()
+
+
+if __name__ == '__main__':
+    index = UnicodeNameIndex()
+    main()