Python中类引用与局部变量遮蔽问题解析及Pygame实践

class Ball:
    # ... (类定义) ...

balls = []

def run():
    # ... (用户输入获取) ...
    while len(balls) < number_balls:
        # ... (收集球的参数) ...
        balls.append(Ball(a, v, r, c, x_pos, y_pos)) # 第一次创建Ball实例时可能正常

    # ... (清屏) ...

    for Ball in balls: # 问题发生在这里！
        Ball.draw(pygame.display.set_mode((width, height))) # 尝试调用Ball类的方法

import pygame
import math

pygame.init()

# 屏幕及物理参数设置
framespd = 30
gravity = 1
t = 0.01
clock = pygame.time.Clock()
width, height = 1000, 1000
pygame.display.set_caption("Orbit Take 1")
screen = pygame.display.set_mode([width, height])

class Ball:
    def __init__(self, angle, velocity, radius, color, x_pos, y_pos):
        # 确保输入参数转换为正确的类型
        self.angle = float(angle)
        self.velocity = float(velocity)
        self.radius = int(radius)
        # 颜色处理可以更灵活，这里简化为字符串，实际应用中需转换为RGB元组
        self.color = self._parse_color(color)
        self.x_pos = int(x_pos)
        self.y_pos = int(y_pos)

    def _parse_color(self, color_str):
        # 简单的颜色字符串到RGB元组转换示例
        if color_str.lower() == 'red':
            return (255, 0, 0)
        elif color_str.lower() == 'green':
            return (0, 255, 0)
        elif color_str.lower() == 'blue':
            return (0, 0, 255)
        # 更多颜色或直接解析RGB字符串
        try:
            # 尝试解析为元组 (r, g, b)
            return eval(color_str)
        except:
            return (255, 255, 255) # 默认白色

    def draw(self):
        # pygame.draw.circle 需要 screen 对象、颜色、中心坐标和半径
        pygame.draw.circle(screen, self.color, (self.x_pos, self.y_pos), self.radius)

    def true_velocity_x(self):
        return self.velocity * math.cos(self.angle)

    def true_velocity_y(self):
        # 这里的重力计算需要更完整的物理模型来更新位置和速度
        true_velocity_y = self.velocity * math.sin(self.angle)
        new_velocity_y = true_velocity_y + (gravity * t)
        return new_velocity_y

    # 简化的位置更新方法，实际应用中需要更复杂的物理模拟
    def update_position(self):
        # 仅为示例，实际需要考虑时间步长、碰撞等
        self.x_pos += int(self.true_velocity_x() * t)
        self.y_pos += int(self.true_velocity_y() * t)


balls = [] # 全局列表用于存储Ball对象

def run():
    game_running = True
    # 首次进入循环前获取球的数量，避免每次循环都询问
    number_balls_to_create = int(input("How many balls: "))

    # 在游戏循环开始前创建所有球
    while len(balls) < number_balls_to_create:
        print(f"\nCreating Ball {len(balls) + 1}/{number_balls_to_create}:")
        a = input("Angle (radians, e.g., 0.5): ")
        v = input("Velocity: ")
        r = input("Radius: ")
        c = input("Color (e.g., 'red' or '(255,0,0)'): ")
        x_pos = input("Initial X position: ")
        y_pos = input("Initial Y position: ")

        # 确保输入转换为正确的类型
        try:
            balls.append(Ball(a, v, r, c, x_pos, y_pos))
        except ValueError as e:
            print(f"Error creating ball: {e}. Please enter valid numbers.")
            continue # 允许用户重新输入

    while game_running:
        clock.tick(framespd)

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                game_running = False

        screen.fill('black') # 每次循环开始时清屏

        # 遍历ball列表，对每个ball实例调用draw方法
        for ball_instance in balls: # 关键修改：避免与全局Ball类名冲突
            ball_instance.draw()
            # ball_instance.update_position() # 如果有位置更新逻辑，在这里调用

        pygame.display.flip() # 更新整个屏幕显示

    pygame.quit()

if __name__ == '__main__':
    run()

def run(BallClass = Ball): # 将全局Ball类作为默认参数传递
    # ...
    # 在需要创建Ball实例的地方，使用BallClass
    balls.append(BallClass(a, v, r, c, x_pos, y_pos))
    # ...
    for Ball in balls: # 这里的Ball仍然是实例
        Ball.draw()