Snake game in terminal, written in Python

Question

I've recently wrote snake game. I Wanted to keep it in pure terminal, without libraries like pygame, tkinter or curses. It works just fine, but i know that the code might be improved. I'm rather junior programmer, and it's my first attempt at 'gamedev', because currently i'm learning Django. I would be grateful if you guys could tell me what should i change :) Here is my code:

#!/usr/bin/python3
import random
import time
import keyboard
import collections
class Board:
 def __init__(self, width: int, height: int, speed: float):
 self.WIDTH = width
 self.HEIGHT = height
 self.SPEED = speed
 self.board = self.__create_board()
 def __create_board(self) -> list:
 return [["□しろいしかく" for _ in range(self.WIDTH)] for _ in range(self.HEIGHT)]
 def print_board(self) -> None:
 print('\n')
 for row in self.board:
 print(row)
class Snake:
 def __init__(self, x_pos, y_pos):
 self.x_pos = x_pos
 self.y_pos = y_pos
 self.head_pos = [self.x_pos, self.y_pos]
 self.body_segments = collections.deque() # doubly end operations, faster than lists
 self.length = 0
 self.apple_pos = [0, 0]
 self.coords = [0, 0]
 self.ate = False
 self.direction = 'up'
 self.spawn_apple()
 def set_empty_square(self) -> None:
 board_obj.board[self.y_pos][self.x_pos] = "□しろいしかく"
 def set_head(self) -> None:
 board_obj.board[self.y_pos][self.x_pos] = "■しかく"
 def draw_body(self) -> None:
 self.body_segments.appendleft(self.coords)
 board_obj.board[self.body_segments[0][1]][self.body_segments[0][0]] = "&"
 if not self.ate:
 board_obj.board[self.body_segments[self.length][1]][self.body_segments[self.length][0]] = "□しろいしかく"
 self.set_head()
 self.body_segments.pop()
 def move(self) -> None:
 self.coords = [self.x_pos, self.y_pos]
 self.set_empty_square()
 if self.direction == "right":
 self.x_pos += 1
 if self.direction == "left":
 self.x_pos -= 1
 if self.direction == "up":
 self.y_pos -= 1
 if self.direction == "down":
 self.y_pos += 1
 self.set_head()
 if self.length >= 1:
 self.draw_body()
 self.head_pos = [self.x_pos, self.y_pos]
 def spawn_apple(self) -> None:
 x = random.randint(0, board_obj.WIDTH-2)
 y = random.randint(0, board_obj.HEIGHT-2)
 apple_pos = [x, y]
 if apple_pos in self.body_segments or apple_pos == self.head_pos:
 self.spawn_apple() # if apple spawned in snake, then run func again with recursion and quit current func
 return
 self.apple_pos = [x, y]
 board_obj.board[y][x] = "●くろまる"
 def eat_apple(self) -> None:
 self.length += 1
 self.ate = True
 def collision(self) -> bool:
 return self.head_pos in self.body_segments or self.y_pos in [board_obj.HEIGHT-1, -1] \
 or self.x_pos in [board_obj.WIDTH-1, -1]
def on_press(_: None):
 for code in keyboard._pressed_events:
 if code == 105:
 snake.direction = 'left'
 elif code == 106:
 snake.direction = 'right'
 elif code == 103:
 snake.direction = 'up'
 elif code == 108:
 snake.direction = 'down'
def start_game(snake: Snake, board_obj: Board):
 snake.set_head()
 board_obj.print_board()
 keyboard.hook(on_press)
 while not snake.collision():
 print("SNAKE: ", snake.head_pos)
 print("BODY: ", snake.body_segments)
 print("APPLE: ", snake.apple_pos)
 snake.move()
 board_obj.print_board()
 snake.ate = False
 if snake.head_pos == snake.apple_pos:
 snake.eat_apple()
 snake.spawn_apple()
 time.sleep(board_obj.SPEED)
 print(f"Game over! Points: {snake.length}")
if __name__ == "__main__":
 board_obj = Board(8, 8, 0.3) # Set: width, height, speed
 snake = Snake(int(board_obj.WIDTH / 2), int(board_obj.HEIGHT / 2)) # Set: snake x and y position
 start_game(snake, board_obj)
```

Answer 1

This is good code for a first post. I'm glad to waste time discussing PEP 8 violations, and seeing a sensible use of the collections module. Having chosen good data structures is a good place to start.

For 2d arrays in Python (unless I am doing numeric heavy lifting, when using numpy is the obvious way to go) I prefer using a dictionary to a list of lists. Something like a named tuple can be used as the key. This makes the board initialization look like:

Pos = collections.namedtuple('position', ['x', 'y'])
...
def __create_board(self) -> None:
 self.board = {(Pos(x, y)) for x in range(self.WIDTH) for y in range(self.HEIGHT)}

This is a fairly big change that will ripple through the code but then you won't have to worry about [y][x] indexing or making temporary (x,y) variables.

Onto some more specific things. First, I think I would define a str method here, rather than having a print method. It adds a hidden dependency to sys.stdout in your code, and makes it harder to unit test.

def print_board(self) -> None:
 print('\n')
 for row in self.board:
 print(row)

Here I would lose the recursion and use a while True/break construction.

if apple_pos in self.body_segments or apple_pos == self.head_pos:
 self.spawn_apple() # if apple spawned in snake, then run func again with recursion 
 return

becomes:

while True:
 ...
 if apple_pos not in self.body_segments and apple_pos != self.head_pos:
 break

I must admit to never having used the keyboard module but _pressed_events doesn't look like it is meant to be part of the API. And I don't know where the magic code numbers come from, or what key (if any) they bind to on my platform.

for code in keyboard._pressed_events:
 if code == 105:
 snake.direction = 'left'

As you never actually use the string directions I might change it to:

for code in keyboard.some_get_event_api_call():
 if code == LEFT_ARROW:
 snake.direction = Pos(-1, 0)

Then you can do the elif thing only once.

Finally:

int(board_obj.WIDTH / 2)

can be just

board_obj.WIDTH // 2

• regorg: Thank you a lot! I've applied all of you advices, except namedtuple, because there would be a lot of work with this code then.. But i will apply it when i'll have some more time :) Also i've splitted whole game in 3 different files and wrote some tests. Thank you again!