Python 设计缺陷--试图阻止交叉导入

我面临的实际问题比这个复杂得多，但这基本上可以归结为：

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

这个错误有点不具体，但我知道这意味着我不应该交叉导入东西：

ImportError: No module named worldobjects

---

我知道这是一个设计缺陷，但我不太确定如何以不同的方式解决这个问题。正如您从代码中看到的，每个单元格都应该每30帧“复制”，唯一可行的方法是将它们添加到

World.py

文件中的数组中。我曾考虑将

worldobjects

数组移动到它自己的文件中，但我觉得这有点脏。有人能帮我解决这个问题吗？

在您的手机中保留指向worldobjects的链接怎么样：

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

---

在单元格中保留指向worldobjects的链接怎么样：

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

---

在单元格中保留指向worldobjects的链接怎么样：

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

---

在单元格中保留指向worldobjects的链接怎么样：

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

---

这是一个很好的例子，说明了为什么全局变量是一个坏主意。与其说细胞需要知道一个称为worldobjects的全局变量的存在，不如在创建时告诉每个细胞这个变量。例如，您可以在构造函数中传递对它的引用。或者创建一个新函数，该函数封装了新单元的创建和有关世界对象的信息

---

或者，您可以将生命周期检查逻辑完全移出单元，并将其放入世界更新中。这对我来说更有意义，因为我不会让每个单元格负责创建新的单元格。

这是一个很好的例子，说明了为什么全局变量是一个坏主意。与其说细胞需要知道一个称为worldobjects的全局变量的存在，不如在创建时告诉每个细胞这个变量。例如，您可以在构造函数中传递对它的引用。或者创建一个新函数，该函数封装了新单元的创建和有关世界对象的信息

---

或者，您可以将生命周期检查逻辑完全移出单元，并将其放入世界更新中。这对我来说更有意义，因为我不会让每个单元格负责创建新的单元格。

这是一个很好的例子，说明了为什么全局变量是一个坏主意。与其说细胞需要知道一个称为worldobjects的全局变量的存在，不如在创建时告诉每个细胞这个变量。例如，您可以在构造函数中传递对它的引用。或者创建一个新函数，该函数封装了新单元的创建和有关世界对象的信息

---

或者，您可以将生命周期检查逻辑完全移出单元，并将其放入世界更新中。这对我来说更有意义，因为我不会让每个单元格负责创建新的单元格。

这是一个很好的例子，说明了为什么全局变量是一个坏主意。与其说细胞需要知道一个称为worldobjects的全局变量的存在，不如在创建时告诉每个细胞这个变量。例如，您可以在构造函数中传递对它的引用。或者创建一个新函数，该函数封装了新单元的创建和有关世界对象的信息

---

或者，您可以将生命周期检查逻辑完全移出单元，并将其放入世界更新中。这实际上对我来说更有意义，因为我不会让每个单元格负责创建新的单元格。

尽管我同意@RickyA在这个问题上的观点以及关于所提供样本的设计的所有其他评论，但我在Flask和WSGI容器中遇到了类似的问题，它们需要globals（至少是app object），因此，需要对循环进口提高警惕。它不是从太空来的，但它是一个讨厌的东西

也许下面的方法可以帮助有类似问题的人（包括这里的海报）。因此，一种可能是在单独的文件中提取全局变量，该文件用作导入中介。它不能解决循环导入类中的所有问题，但在适用的情况下非常简单

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

WorldObjects.py

objects = []

---

尽管我同意@RickyA在这个问题上的意见以及关于所提供样品设计的所有其他意见，但我在Flask和WSGI容器上遇到了类似的问题，它们需要globals（至少是app object），因此需要对循环导入提高警惕。它不是从太空来的，但它是一个讨厌的东西

也许下面的方法可以帮助有类似问题的人（包括这里的海报）。因此，一种可能是在单独的文件中提取全局变量，该文件用作导入中介。它不能解决循环导入类中的所有问题，但在适用的情况下非常简单

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

WorldObjects.py

objects = []

---

尽管我同意@RickyA在这个问题上的意见以及关于所提供样品设计的所有其他意见，但我在Flask和WSGI容器上遇到了类似的问题，它们需要globals（至少是app object），因此需要对循环导入提高警惕。它不是从太空来的，但它是一个讨厌的东西

也许下面的方法可以帮助有类似问题的人（包括这里的海报）。因此，一种可能是在单独的文件中提取全局变量，该文件用作导入中介。它不能解决循环导入类中的所有问题，但在适用的情况下非常简单

Cell.py

from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            worldobjects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

#from World import worldobjects #This is the problem, python does not like cross imports

class Cell:
    def __init__(self, worldobjects):
        self.lifetime = 0 #Keep track of frames spent 'alive'
        self.worldobjects = worldobjects

    def update(self):
        self.lifetime += 1 
        if self.lifetime > 30:
            self.worldobjects.append(Cell(self.worldobjects)) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime 

import WorldObjects

class Cell:
    def __init__(self):
        self.lifetime = 0 #Keep track of frames spent 'alive'

    def update(self):

        self.lifetime += 1 
        if self.lifetime > 30:
            WorldObjects.objects.append(Cell()) #Add a new cell to the world
            self.lifetime = 0 #Reset lifetime

World.py

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell())

while True:
    for obj in worldobjects:
        obj.update()

import Cell

worldobjects = []

for i in range(10): #create  a bunch of initial cells
    worldobjects.append(Cell.Cell(worldobjects))

while True:
    for obj in worldobjects:
        obj.update()

import Cell
import WorldObjects

for i in range(10): #create  a bunch of initial cells
    WorldObjects.objects.append(Cell.Cell())

while True:
    for obj in WorldObjects.objects:
        obj.update()

WorldObjects.py

objects = []

---

虽然我同意@RickyA关于这件事的看法以及关于所提供样品设计的所有其他意见，但我在Flas上遇到了类似的问题