CODEWITHSUNDEEP
python
Frederic Bastiat
Frederic Bastiat

Reputation: 693

attributeError class intance has no attribute '__getitem__'

I've created a MarblesBoard class which I use to instantiate new MarblesBoard objects. I want to solve the board using the Solver class. 

class MarblesBoard:
    def __init__(self, marbles):
        self.input = list(marbles) 
        print(marbles)
    def switch(self):
        self.input[1], self.input[0] = self.input[0], self.input[1]
        print self.input     
    def rotate(self):
        return self.input[1:] + self.input[:1]
        print self.input
    def is_solved(self):
        if all(self.input[i] <= self.input[i+1] for i in range(len(self.input)-1)):
            return True
            print "True"
        else:
            print "Not solved!"

board = MarblesBoard((3,6,7,4,1,0,8,2,5))
board.switch()
board.rotate()
board.is_solved()
board

Works as expected.

class Solver:
    def __init__(self, MarblesBoard):
        print self
        self.input = MarblesBoard
    def solve(self):
        if self.input[0] & self.input[1] != 0:
            if self.input[1] < self.input[0]:
                self.input.switch()
            else:
                self.input.rotate()
        else:
            self.input.rotate()

player = Solver(board)
player.solve()

Gives me AttributeError: MarblesBoard instance has no attribute 'getitem' in reference to the self.input lines in the solve function.

Upvotes: 0

Views: 56

Answers (1)

tdelaney
tdelaney

Reputation: 77407

self.input is an instance of the MarblesBoard class, which contains a variable also called input. MarblesBoard doesn't implement a __getitem__ method to get its internal self.input list so you have to reach into it yourself

if self.input.input[0] & self.input.input[1] != 0:

That first input gets the MarblesBoard instance and the second input gets the list inside the instance.

Suppose I implemented Solver with a more descriptive variable name

class Solver:
    def __init__(self, MarblesBoard):
        print self
        self.marbles_board = MarblesBoard
        ...

Then using it would be more self evident

    def solve(self):
        if self.marble_board.input[0] & self.marble_board.input[1] != 0:
        ...

Upvotes: 1

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