introduce a game class

game.py

+from player import Player
+import selectors
+import socket
+
+class Game:
+    def __init__(self):
+        self.players = []
+        self.sock = socket.socket()
+        self.sock.bind(('0.0.0.0', 1234))
+        self.sock.listen(100)
+        self.sel = selectors.DefaultSelector()
+        self.sel.register(self.sock, selectors.EVENT_READ, self.accept)
+    
+    def accept(self, sock, mask):
+        assert sock == self.sock
+        conn, addr = sock.accept()  # Should be ready
+        player = Player(self, conn)
+        self.players.append(player)
+        self.sel.register(conn, selectors.EVENT_READ, player.read)
+    
+    def removePlayer(self, player):
+        assert player in self.players
+        player.close()
+        self.players.remove(player)
+        assert player not in self.players # this ensure the player was in only once
+    
+    def close(self):
+        for player in self.players:
+            player.close()
+        self.players.clear()
+        self.sock.close()
+    
+    def run(self):
+        while True:
+            events = self.sel.select()
+            for key, mask in events:
+                callback = key.data
+                callback(key.fileobj, mask)

main.py

 #!/usr/bin/python3
+from game import Game
 
-import selectors
-import socket
-import atexit
-from player import Player
-
-sel = selectors.DefaultSelector()
-players = []
-
-def accept(sock, mask):
-	conn, addr = sock.accept()  # Should be ready
-	player = Player(sel, conn)
-	players.append(player)
-	sel.register(conn, selectors.EVENT_READ, player.read)
-
-sock = socket.socket()
-sock.bind(('0.0.0.0', 1234))
-sock.listen(100)
-sel.register(sock, selectors.EVENT_READ, accept)
+game = Game()
 
 try:
-    while True:
-        events = sel.select()
-        for key, mask in events:
-            callback = key.data
-            callback(key.fileobj, mask)
+    game.run()
 finally:
-    sock.close()
-    for player in players:
-        player.close()
+    game.close()
+
 

player.py

 from util import *
 
 class Player:
-    def __init__(self, sel, conn):
+    def __init__(self, game, conn):
         self.buffer = b""
-        self.sel = sel
+        self.game = game
         self.conn = conn
     
     # low-level functions
@@ -11,7 +11,7 @@ class Player:
         assert type(data) == str
         send_async(self.conn, (data+"\n").encode('utf-8'))
     
-    def close(self):
+    def close(self): # only to be called by Game - it has to remove us from its list
         self.conn.close()
     
     def read(self, conn, mask):
@@ -25,9 +25,7 @@ class Player:
                 self.buffer = self.buffer[pos+1:]
                 self.readCmd(cmd.decode('utf-8'))
         else:
-            log_stdout('closing', conn)
-            self.sel.unregister(conn)
-            conn.close()
+            self.game.removePlayer(self)
     
     # high(er)-level functions
     def readCmd(self, cmd):