Why are my different instance variables linking together in python -

i new python did digging , understand member variable of class update in instances of class regardless of instance modified with. however, doesn't seem same should happen instance variables when run block of code...

class game(object):      def__init__(self, active_turn, board):          self.active_turn = active_turn          self.board = board   game = game(1,[1,0,0,0,0,0,0,0,0])  move = 3  print(game.board, "\n")  possible_game = game(game.active_turn*-1,game.board)  print(game.board) print(possible_game.board, "\n")  possible_game.board[move] = possible_game.active_turn  print(game.board) print(possible_game.board, "\n")  game.board[move+1] = game.active_turn  print(game.board) print(possible_game.board) 

i output...

[1, 0, 0, 0, 0, 0, 0, 0, 0]   [1, 0, 0, 0, 0, 0, 0, 0, 0] [1, 0, 0, 0, 0, 0, 0, 0, 0]   [1, 0, 0, -1, 0, 0, 0, 0, 0] [1, 0, 0, -1, 0, 0, 0, 0, 0]   [1, 0, 0, -1, 1, 0, 0, 0, 0] [1, 0, 0, -1, 1, 0, 0, 0, 0] 

the board variable updating in each instance of game class though changing in 1 of them. know why happening , avoid it?

thanks, nick

you're using same board when create both instances - when 1 of them updates board - change reflected in other well.

game = game(1,[1,0,0,0,0,0,0,0,0]) # first instance - create board here ... possible_game = game(game.active_turn*-1,game.board) # second instance - pass same board (game.board) constructor