Python and Pygame Value is updating but update is not taken into account by code?

Question

I wanted to ask you for your help. I am following tutorial about creating alien game but I modified it a little bit and I cannot get it to work properly. I have value for alien_speed in settings pyfile. I am modifying it in method increase_speed and I am printing it (and it is actually growing like I want it to). But aliens have still the same speed. I don't understand why it is not working. Can maybe someone point me in right direction ?

settings.py:

import pygame

resolution_width = 1280
resolution_height = 720

class Settings:
    """A class to store all settings for Space Impact."""

    def __init__(self):
        """Initialize the game's static settings."""
        # Screen settings
        # This line is needed to avoid error: No video mode has been set
        self.screen = pygame.display.set_mode((0, 0))
        self.screen_width = resolution_width
        self.screen_height = resolution_height
        self.bg_image = pygame.image.load("images/background_1.png").convert()

        # Bullet settings
        self.bullet_speed = self.screen_width*0.01
        self.bullet_width = self.screen_width*0.02
        self.bullet_height = self.screen_height*0.02
        self.bullet_color = (0, 0, 0)

        # How quickly the game speeds up
        self.speedup_scale = 999
        # Ship Settings
        self.ships_limit = 3



        self.initialize_dynamic_settings()

    def initialize_dynamic_settings(self):
        self.alien_speed = self.screen_width*0.003

    def increase_speed(self):
        """Increase speed settings."""
        self.alien_speed *= self.speedup_scale
        print(self.alien_speed)

alien.py:

import pygame
from pygame.sprite import Sprite
from settings import Settings
import random


class Alien(Sprite):
    """A class to represent a single alien."""

    def __init__(self, space_impact):
        """Initialize alien and set it's starting position."""
        super().__init__()
        self.screen = space_impact.screen
        self.settings = Settings()

        # Load the alien image and set it's rect attribute.
        self.index = 0
        self.timer = 0
        self.image = []
        self.image.append(pygame.image.load('images/alien_1.png'))
        self.image.append(pygame.image.load('images/alien_2.png'))
        self.image = self.image[self.index]
        self.image = pygame.transform.scale(self.image, (80 * int(self.settings.screen_width * 0.0019),
                                            40 * int(self.settings.screen_width*0.0019)))

        self.rect = self.image.get_rect()

        random_height = random.uniform(0.01, 0.85)
        random_width = random.uniform(1.1, 2)
        self.rect.x = int(self.settings.screen_width * random_width)
        self.rect.y = int(self.settings.screen_height * random_height)

        # Store the alien's exact horizontal position.
        self.x = float(self.rect.x)

    def update(self):
        """Move the alien to left side."""
        self.x -= self.settings.alien_speed
        self.rect.x = self.x

        if self.timer >= 0 and self.timer <= 25:
            self.timer += 1
            self.index = 0

        elif self.timer >= 26 and self.timer < 50:
            self.timer += 1
            self.index = 1
        else:
            self.timer = 0

        if self.index == 0:
            self.image = pygame.image.load("images/alien_1.png")
        if self.index == 1:
            self.image = pygame.image.load("images/alien_2.png")

        self.image = pygame.transform.scale(self.image, (80 * int(self.settings.screen_width * 0.0019),
                                            40 * int(self.settings.screen_width * 0.0019)))

Edit: Of course in my main file I am calling function self.settings.increase_speed()

---

Edit2:

import pygame

resolution_width = 1280
resolution_height = 720

class Settings:
    """A class to store all settings for Space Impact."""

    screen_width = resolution_width
    alien_speed = screen_width * 0.003
    speedup_scale = 3
    alien_speed *= speedup_scale

    def __init__(self):
        """Initialize the game's static settings."""
        # Screen settings
        # This line is needed to avoid error: No video mode has been set
        self.screen = pygame.display.set_mode((0, 0))
        self.screen_width = resolution_width
        self.screen_height = resolution_height
        self.bg_image = pygame.image.load("images/background_1.png").convert()

        # Bullet settings
        self.bullet_speed = self.screen_width*0.01
        self.bullet_width = self.screen_width*0.02
        self.bullet_height = self.screen_height*0.02
        self.bullet_color = (0, 0, 0)

        # How quickly the game speeds up
        self.speedup_scale = 3
        # Ship Settings
        self.ships_limit = 3




    def increase_speed(self):
        """Increase speed settings."""
        global alien_speed
        global speedup_scale
        alien_speed *= speedup_scale
        print(self.alien_speed)

Edit3:

I managed to fix it thanks to your comments. Thank you :)

Answer 1

Settings seems to contain global settings, but each Alien creates its own instance of Settings:

class Alien(Sprite):
   """A class to represent a single alien."""

   def __init__(self, space_impact):
       # [...]

       self.settings = Settings()

That means that each Alien has its own Settings and thus alien_speed.

Either you've to update the settings in each instance of Alien, that means you've to call increase_speed() for each Alien separately.

Or just pass a singleton instance of Settings to Aliens. That makes it sufficient to update the singleton instance:

class Alien(Sprite):
    """A class to represent a single alien."""

    def __init__(self, space_impact, settings):
        """Initialize alien and set it's starting position."""
        super().__init__()
        self.screen = space_impact.screen
        self.settings = settings
        # [...]

In "main":

alien = Alien(space_impact, self.settings)

Another option would be to turn the attributes of the class Settings to class attributes. Instance attribute are unique to each instance, but class attributes are shared by all instances.