Question

我发现我认为python 3.4的特殊行为。我制作了这些小文件来说明我面临的问题。

为了关注这个问题，我现在有一个python程序（模块），peculiar.py，包含一个类和一些函数。其中一个函数是从Point类实例化点。当我左键单击pygame窗口时，通过此函数add_point从类Point实例化一个点。在命令窗口中，列出了以这种方式创建的实例。一切都很好。正如我们所看到的那样，crated点被添加到points_list并在命令窗口中列出。

右键单击窗口会使另一个模块（pec_controls.py）中的函数调用的函数（add_point）完全相同。然后实例化一个点，但它似乎被添加到一个新的或不同的points_list，只添加通过右键单击窗口实例化的点。如果我们在左右单击窗口之间切换，则该类会在points_list的两个不同版本之间切换。

如果直接从pec_controls.py调用该类，我可以理解这种行为，即该点在pec_control.py中实例化，但不是现在，当它是peculiar.py中调用该类的相同函数时所有实例。当我右键单击时，我有点“将范围”传递给pec_control模块，但我认为当该模块然后调用add_point返回peculiar.py时，应该期望返回范围。温和地说，你调用函数的地方对于它来说是非常重要的，或者是一个类的行为。

有人可以通过python解释这种行为背后的基本原理吗？有没有我忘了，让所有实例出现在同一个列表中？

这是pec_controls.py：

import peculiar, sys, pygame

def clicked_right():
    peculiar.add_point()

这里是peculiar.py：

# peculiar.py
# Sample to show peculiar behaviour by python 3.4, or python in general?
# Left clicking window instantiates point by this module alone(see command window).
# Right clicking window instantiates point from pec_controls.py module. 
# Right clicking, instead of calling add_point function directly, as left clicking does, calls     function in pec_controls.py, which then calls the add_point function in this module.
# What is peculiar is that this is resulting in Class Point seeming to make a new list of the global list points_list,
# only containing the items instantiated from pec_controls module(i.e. by right clicking window) ref. command window .
# Left clicking again, makes the Class go back to the original list, adding "leftclicked" point instances as usual.
# Apparently there is now two different lists? Is this a bug or intended? 

import pygame, sys, pec_controls
from pygame.locals import *

FPS = 10
points_list = []
class Point():
    def __init__(self):
        points_list.append(self)
        self.position = (10 * len(points_list), 10 * len(points_list))
        print("Class says:    ",len(points_list), "points")                     

    def update(self):
        self.rect.x = self.position[0]
        self.rect.y = self.position[1]
        pass

def add_point( x = None, y = None):
    display_frame()
    point = Point()
    for i in points_list:                                                       # The points created by calling the class from controls.py via btn_add_point_clicked_left.
        print ("add_point says", i, i.position)                                 # ref: Display frame which prints out the points made by calling the class from main
   print ("add_point", points_list)                                             # This writes out points in points_list                     !!!!!!!!


def process_events():
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                return True
            if event.type == pygame.MOUSEBUTTONUP :
                if event.button == 1:
                    add_point()                                     # Instantiates a point via btn_add_point_clicked. (Ok/Normal)
                    print("Left Click")
                elif event.button == 3:
                    pec_controls.clicked_right()                                # Instantiates a point via pec_controls module via add_point. (Peculiar result !!!!)
                    print("Right Click")    
                pass
        return False

def display_frame():                                        
    for i in points_list:                                   # Writes out the points in the global list points_list
        print ("display says", i, i.position)                   # 
    print("display", points_list)                               # 

def main():                                                 # Main function
    pygame.init()
    main.screen = pygame.display.set_mode((200,200),0,32)
    main.clock = pygame.time.Clock()

    point = Point()                                         # Instantiates a point from main of this module
    point.position =(100,200)

    add_point()                                             # Instatiates a point from main via the function add_point

    main.done = False
    while not main.done:                                    
        main.done = process_events()
        main.clock.tick(FPS)
        #display_frame()

    pygame.quit()   

if __name__ == "__main__":
    main()

Answer 1

您遇到的问题是，当peculiar.py作为脚本运行时，它不会被视为peculiar模块。它被认为是__main__模块。导入peculiar将再次运行该文件，生成Point类，points_list列表的单独副本，等等。

我建议将程序的main功能分离到单独的文件中，该文件导入peculiar并从peculiar模块调用所有版本。或者，您可以在import peculiar; peculiar.main()块中使用if __name__ == "__main__"。

Python模块 - 范围

1 个答案: