无论如何要从其他模块覆盖 class，同时将它的方法保留在 python 中

Question

为了说明我的问题，这里有3个模块：

这是模块A

'''
lets call this module the parent, it regroups multiple classes with several
method each
'''

class Rectangle():
    '''
    The basic rectangle class that is parent for other classes in this
    module
    '''
    def __init__(self, x_length, y_length):
        self.x_length = x_length
        self.y_length = y_length

    def create_points(self):
        '''
        Basic geometrical method 
        '''
        self.point_1 = [x_length/2, y_length/2]
        self.point_2 = [-x_length/2, y_length/2]
        self.point_3 = [-x_length/2, -y_length/2]
        self.point_4 = [x_length/2, -y_length/2]

class Square(Rectangle):
    '''
    The square that is a rectangle with two identical sides
    '''
    def __init__(self, side_dim):
        super().__init__(side_dim, side_dim)

class SquareCollection():
    '''
    Creates a composition relation with an other class of the module
    '''
    def __init__(self, dim_list):
        '''
        The constructor creates a square for every float in the given list
        '''
        for val in dim_list:
            try:
                self.element.append(Square(val))
            except AttributeError:
                self.element = [Square(val)]

    def create_points(self):
        for elmt in self.element:
            elmt.create_points()

这是模块 B1

'''
lets call this module the child 1, it redefines the classes from the parent but
with an additionnal method specific for its use case
'''
import Module_A as ma

class Rectangle(ma.Rectangle):
    '''
    The basic rectangle class that is parent for other classes in this
    module
    '''
    def module_specific_method(self):
        self.special_attribute_1 = True

class Square(ma.Square):
    '''
    The square that is a rectangle with two identical sides
    '''
    def module_specific_method(self):
        self.special_attribute_1 = True

class SquareCollection(ma.SquareCollection):
    '''
    Redefining the SquareCollection with an additionnal method
    '''
    def module_specific_method(self):
        for elmt in self.element:
            elmt.module_specific_method()

这是模块 B2

'''
lets call this module the child 2, it redefines the classes from the parent but
with an additionnal method specific for its use case
This module is a copy of Module_B2 and is used to justify the used code
structure
'''
import Module_A as ma

class Rectangle(ma.Rectangle):
    '''
    The basic rectangle class that is parent for other classes in this
    module
    '''
    def module_specific_method(self):
        self.special_attribute_2 = True

class Square(ma.Square):
    '''
    The square that is a rectangle with two identical sides
    '''
    def module_specific_method(self):
        self.special_attribute_2 = True

class SquareCollection(ma.SquareCollection):
    '''
    Redefining the SquareCollection with an additionnal method
    '''
    def module_specific_method(self):
        for elmt in self.element:
            elmt.module_specific_method()

当我导入模块 B2 时创建一个 sc = SquareCollection([4, 3.5, 0.8]) 实例然后运行 sc.module_specific_method() 我得到一个 AttributeError 用于被调用的 Square classes 是使用 A 模块创建的，因为 SquareCollection class 继承自 A 模块中定义的那个，它本身根据 class 定义创建多个 Square 实例在同一个模块中。 AttributeError 是预期的，因为我在 A 模块的任何地方都定义了这个 module_specific_method.

由于我的代码结构和我目前的使用方式，我使用的是模块 B1 或模块 B2。我目前通过重写模块 A 中包含的所有内容两次（一个在 B1 中，另一个在 B2 中）来避免这个问题。因为我正在重构我所有的代码，所以我希望我可以删除所有重复的代码并将其放入一个“通用”模块中，如上面的简化示例所示。

模块 A 中的 classes 怎么可能 inherit/point 回到我调用它的 B 模块？

我希望我的问题很清楚，因为我真的很难把它形式化。

干杯！

Answer 1

您可以通过使基础 SquareCollection 中使用的 Square class 成为集合 class 的属性来实现此目的，这样它就不会被硬编码，而是变成也可以被 subclasses 显式覆盖：

# Module_A
class Square:
    pass      # implement stuff here

class SquareCollection
    BaseItem = Square    # the "class that is collected here"

    def __init__(self, dim_list):
        # spawn BaseItem instances here, which are Square by default,
        # but might be set to something else in a subclass
        self.element = [self.BaseItem(val) for val in dim_list]

# Module_B1
import Module_A as ma

class Square(ma.Square):
     pass

class SquareCollection(ma.SquareCollection):
    # override the collection's BaseItem with this module's Square class,
    # but keep the rest of the SquareCollection code the same
    BaseItem = Square

无论如何要从其他模块覆盖 class，同时将它的方法保留在 python 中

Is there anyway to override class from other module while keeping it's methods in python

python

python-3.x

class

inheritance

composition