问题描述
我发现我认为python 3.4的独特行为。为了说明这个问题，我现在有一个python程序（模块），peculiar.py，包含一个Python程序类和一些功能。其中一个功能是实例化类Point中的点。
当我离开pygame窗口时，一个点通过这个函数add_point从类Point实例化。在命令窗口中列出了以这种方式创建的实例。这一切都可以。正如我们所看到的那样，积分点被添加到points_list并列在命令窗口中。
右键单击窗口使得函数调用相同的函数（add_point）在另一个模块（pec_controls.py）中。
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中，仅添加通过右击窗口实例化的点。如果我们在左右窗口之间切换，类将在两个不同版本的points_list之间切换。
如果直接从pec_controls调用类，我可以理解此行为.py，即该点在pec_control.py中实例化，但与现在不同，当它与peculiar.py中的所有实例中调用该类的函数完全相同时。
当我点击鼠标右键时，我有点将范围传递给pec_control模块，但我认为应该期望返回范围，然后该模块再调用add_point，返回到peculiar.py。
这是非常令人意外的，可以轻微地说，你调用一个函数的地方对它是重要的，或者是一个类的行为。
有人可以解释python背后的这种行为的基本原理？
是否有我忘记的东西，让所有实例出现在同一个列表中？
这里是pec_controls.py：
中的peculiar.main（）I found what I think is peculiar behaviour by python 3.4. I made these small files to illustrate the problem I am facing.
To focus on the problem, I now have a python program(module), peculiar.py, containing a class, and some functions. One of the functions are instantiating points from the class Point. When I left click the pygame window, a point is instantiated from the class Point, by this function, add_point. In the command window the instances created this way is listed. Everything is ok with this. As we can see the points crated are added to the points_list and listed in the command window.
Right clicking the window makes the very same function (add_point) called by a function in another module (pec_controls.py). A point is then instantiated, but it seems to be added to a new or different points_list, adding only points instantiated by right clicking the window. If we toggle between right and left clicking the window, the class toggles between two different versions of the points_list.
I could understand this behavior if the class was called directly from pec_controls.py, i.e. the point was instantiated in pec_control.py, but not as now, when it is the very same function in peculiar.py that calls the class in all instances. I am kind of "passing the scope" to pec_control module when I right click, but I think one should expect the scope to be returned, when that module then calls add_point, back in peculiar.py. It is very unexpected to put it mildly that where you call a function from is significant to it's, and or, a class's behavior.
Could someone explain the rationale behind this behavior by python? Is there something I forgot, to make all the instances appear in the same list?
Here is pec_controls.py:
import peculiar, sys, pygame def clicked_right(): peculiar.add_point()and here is 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()解决方案The problem you're running into is that when peculiar.py is run as a script, it is not considered to be the peculiar module. It is considered to be the __main__ module. Importing peculiar will run the file again, producing a separate copy of the Point class, the points_list list, and so on.
I recommend separating your program's main functionality into a separate file that imports peculiar and calls the versions of everything from the peculiar module. Alternatively, you can use import peculiar; peculiar.main() in your if __name__ == "__main__" block.
这篇关于Python模块 - 范围的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！