My minesweeper program works just fine until I click on the top left tile. Everything looks fine - python-3.x

Question

I am attempting to make minesweeper in Python by using tkinter. When the program checks for bombs, it works just fine unless the tile clicked is at 0, 0 (top left), in which case the program always has tileNorth and tileWest True, causing the program to check a variable that doesn't exist. This causes an error and leaves the 0, 0 tile blank. The checking works in every other tile, including corners, just not the top left. This should not be happening.
TLDR:
My minesweeper program works just fine, but it always messes up at 0, 0 and creates an error. I don't understand what's wrong...
The Error:
Exception in Tkinter callback
Traceback (most recent call last):
File "/usr/lib/python3.7/tkinter/__init__.py", line 1705, in __call__
return self.func(*args)
File "<string>", line 11, in <lambda>
File "/home/pi/Documents/Python/Minesweeper/Minesweeper.py", line 133, in tileClicked
stringVar_{x}_{y}.set(tileValue)""")
File "<string>", line 56
if bomb_-1_-1 == True:
^
SyntaxError: invalid token
It mentions bomb_-1_-1 which doesn't exist and can't exist... This is why that one if statement needs to work.
My Code:
import random
import tkinter
# Functions
def tileClicked(x, y): # Function is ran when a tile is clicked. The tile is defined by the inputted 'x' and 'y' values.
exec(f"""
global tileNorth, tileEast, tileSouth, tileWest
if y > 0:
tileNorth = True
else:
tileNorth = False
if x < game.size[0] - 1:
tileEast = True
else:
tileEast = False
if y < game.size[1] - 1:
tileSouth = True
else:
tileSouth = False
if x > 0:
tileWest = True
else:
tileWest = False""")
print(f"""{tileNorth}
{tileEast}
{tileSouth}
{tileWest}
DIV""")
exec(f"""
print("{x}, {y}")
if bomb_{x}_{y} == True:
stringVar_{x}_{y}.set("Bomb")
game.failed = True
if x == 0 and y == 0:
tileValue = int(0)
if tileNorth == True:
if tileEast == True:
if bomb_{x + 1}_{y - 1} == True:
tileValue += 1
if tileEast == True:
if bomb_{x + 1}_{y} == True:
tileValue += 1
if tileSouth == True:
if tileEast == True:
if bomb_{x + 1}_{y + 1} == True:
tileValue += 1
if tileWest == True:
if bomb_{x - 1}_{y + 1} == True:
tileValue += 1
if bomb_{x}_{y + 1} == True:
tileValue += 1
if tileWest == True:
if bomb_{x - 1}_{y} == True:
tileValue += 1
else:
tileValue = int(0)
if tileNorth == True:
if tileEast == True:
if bomb_{x + 1}_{y - 1} == True:
tileValue += 1
if tileWest == True:
if bomb_{x - 1}_{y - 1} == True:
tileValue += 1
if bomb_{x}_{y - 1} == True:
tileValue += 1
if tileEast == True:
if bomb_{x + 1}_{y} == True:
tileValue += 1
if tileSouth == True:
if tileEast == True:
if bomb_{x + 1}_{y + 1} == True:
tileValue += 1
if tileWest == True:
if bomb_{x - 1}_{y + 1} == True:
tileValue += 1
if bomb_{x}_{y + 1} == True:
tileValue += 1
if tileWest == True:
if bomb_{x - 1}_{y} == True:
tileValue += 1
if tileValue == 0:
tileValue = "Clear"
stringVar_{x}_{y}.set(tileValue)""")
# Classes
class game:
title = "Minesweeper"
bg = "white"
fg = "black"
size = [10, 10]
tileWidth = 3
tileHeight = 2
failed = False
bombFrequency = 4
flagMode = False
# Execution
window = tkinter.Tk() # The window.
window.title(game.title)
window.config(bg = game.bg)
mainFrame = tkinter.Frame(window, bg = game.bg) # Main frame that everything is located in.
titleFrame = tkinter.Frame(mainFrame, bg = game.bg) # Title frame.
titleLabel = tkinter.Label(titleFrame, bg = game.bg, fg = game.fg, text = game.title, font = "none 20").grid(row = 0, column = 0)
titleFrame.grid(row = 0, column = 0)
tileFrame = tkinter.Frame(mainFrame, bg = game.bg) # Frame where tiles are located.
x = 0
y = 0
for tiles_x in range(game.size[0]): # Generates tiles.
for tiles_y in range(game.size[1]):
exec(f"""global tile_{x}_{y}, stringVar_{x}_{y}, bomb_{x}_{y}
bomb_{x}_{y} = random.randint(1, game.bombFrequency)
if bomb_{x}_{y} == 1:
bomb_{x}_{y} = True
else:
bomb_{x}_{y} = False
stringVar_{x}_{y} = tkinter.StringVar(tileFrame)
tile_{x}_{y} = tkinter.Button(tileFrame, bg = 'lightgrey', fg = 'black', width = game.tileWidth, height = game.tileHeight, textvariable = stringVar_{x}_{y}, command = lambda: tileClicked({x}, {y})).grid(row = {y}, column = {x})""")
y += 1
x += 1
y = 0
tileFrame.grid(row = 1, column = 0)
mainFrame.pack() # The main frame is packed so everything is centered.
window.mainloop()
I don't care if you think dynamic variables are inefficient, it's my choice. I don't want people to comment on my methods of accomplishing a task... unless it's causing the problem...
Thanks!

Answer 1

Using dynamic variables is bad practice, and your experience is a good demonstration why.
Variable names cannot have a minus sign in them. The minus sign is interpreted as the arithmetic operator. So bomb_-1_-1 is interpreted as bomb_ - 1_ - 1. The bomb_ part is understood as a variable name, the 1 as a number, but the underscore following that number is triggering the syntax error.
This also demonstrates that dynamic code is not that great: syntax errors only pop up when certain circumstances are created (like selecting a particular cell).
A quick fix, just to show a work around, is to test first the values of x and y:
if {x} >= 0 and {y} >= 0 and bomb_{x}_{y} == True:
You would have to do similar tests for any other place where you create a dynamic reference like that. So also:
if {x} >= 1 and {y} >= 1 and bomb_{x-1}_{y-1} == True:
...etc.
But this is really patching a terrible design.
Note that even if only one of the variables is negative, you'll evaluate an expression that you did not really intend. You could get this for when only y == -1: bomb_5_-1. This produces no syntax error, but it evaluates as bomb_5_ minus 1. Obviously that is not intended by the algorithm.
Instead of dynamic variables and parsing code at run-time, use lists. They can be nested to have the 2D coverage.