Python Forum

Hello,

Probably a newbie question here.... but is there any way to dynamically pass arguments to a function? I am accessing a class from someone else's code, and I can't modify it.

attackers = board.attackers(chess.BLACK, chess.A7)

The first argument can either be (chess.BLACK) or (chess.WHITE), and the second can be anything from (chess.A1) to (chess.H8)... so a total of 128 combinations.

I would like my program to be able to loop through each possible argument for this method, but I don't want to hardcode 128 lines of code in to my program.

If I try to do something intuitive like this, it doesn't work...

color = 'BLACK'
square = 'A7'

attackers = board.attackers(chess.color, chess.square)

Error:
AttributeError: module 'chess' has no attribute 'color'

Because it's trying to read the attribute literally, rather than treating it as a variable.

Can an attribute be a variable? How would I handle this?

Nevermind, I figured it out.

color = [chess.BLACK, chess.WHITE]
square = [chess.A7, chess.C7]

a = 1

attackers = board.attackers(color[a], square[a])

If anybody else ever wants to do this, here's how I did it. It will accept a slice or an integer, but not an immutable object like a string, which was the problem I was having.

Thanks everyone.

You can look up attributes by name.

class ChessThing():
    """Standing for chess which I do not have"""
    def __init__(self):
        self.BLACK = 100
        self.WHITE = 200
        self.A0 = 0
        self.A1 = 1
        self.A2 = 2
        self.A3 = 3
        self.A4 = 4
        self.A5 = 5
        self.A6 = 6
        self.A7 = 7

chess = ChessThing()

# Get attributes from chess using the attribute name
colors = [getattr(chess, color) for color in ['BLACK', 'WHITE']]
squares = [getattr(chess, f'{r}{c}') for r in ['A'] for c in range(8)]

print(colors)
print(squares)

Output:
[100, 200]
[0, 1, 2, 3, 4, 5, 6, 7]

Before doing that I would exhaust all efforts to see if there is any kind of collection for the A0..H7. But if you have to, you can get all 64:

squares = [getattr(chess, f'{r}{c}') for r in ['ABCDEFGH'] for c in range(8)]