PYTHON — Discard Incorrect Game States in Python

In the software world, the moment you start using someone else’s software, you are living in their world, under their philosophy. — Richard Stallman

## Discard Incorrect Game States in Python

When creating a game in Python, it’s important to discard incorrect game states to ensure that the game functions as intended. In this tutorial, we’ll walk through the process of implementing a validation layer to reject invalid game states in a Tic-Tac-Toe game using Python.

Overview

We’ll start by implementing a familiar post-initialization hook in the GameState class that delegates the processing to another function, validate_game_state(). This function will receive an instance of the game state containing the grid of cells and the starting player.

class GameState:
    def __init__(self, grid, starting_player):
        self.grid = grid
        self.starting_player = starting_player
        self.validate_game_state()

We’ll split the validation into smaller and more focused stages by delegating bits of the state further down in our validators module.

Validate Game State

def validate_game_state(self):
    self.validate_mark_proportion()
    self.validate_starting_player()
    self.validate_winner()

To prevent instantiating a game state with an incorrect number of a player’s marks in the grid, we’ll take the proportion of naughts to crosses into account. The number of marks left by one player must be either the same or greater by exactly one compared to the number of marks left by the other player.

Handling Invalid States

class InvalidGameStateError(Exception):
    pass

We’ll signal an invalid state by raising a custom exception, InvalidGameStateError, defined in another module.

Further Validations

We’ll also validate the starting player’s mark and the number of marks left on the grid. There can only be one winner, and depending on who started the game, the ratio of Xs and Os left on the grid will be different.

Conclusion

In this tutorial, we’ve encapsulated the Tic-Tac-Toe game’s rules in Python code by implementing a validation layer to discard incorrect game states. By systematically validating game states, we ensure that the game functions as expected. In the next step, we’ll write code to produce new game states by simulating players’ moves.

Now that you understand the process of discarding incorrect game states in Python, you can apply similar validation techniques to your own game development projects.

By implementing the validation layer as outlined in this tutorial, you can ensure that your game functions as intended. The provided Python code snippets and examples demonstrate how to discard incorrect game states when developing a game. This tutorial serves as a foundational guide for implementing a validation layer to reject invalid game states in Python.