我如何有引用键:值更新时，他们的引用键:值更新在一个类?

Question

在下面的代码中，我如何更改set_ref方法，使其自动更改为引用键的值，以匹配每次打印表单时引用的键的值?

例如:

在下面的代码中，我将A1的值设置为10，然后我使用set_ref方法使A3引用A1，因此它也是10。现在，当我把A1的值设为20时，A3仍然是10。我需要做什么才能自动将A3值更改为20?

#create sheets class with constructor to initialize "cells" instance variable as a dictionary
class Sheet:
def __init__(self) -> None:
self.cells = dict()
# set_value method takes key as a string and value as an int, set cells with
# key index along with its value
def set_value(self, key: string, value: int) -> None:
self.cells[key] = value
# get_value method takes the key as a string and return the value of the cell
# based on key index
def get_value(self, key: string) -> int:
return self.cells[key]

# set ref takes new key, the reference key and the old key, the key being referenced
# use set value method to set new value that has new key and the value of the key that it references
def set_ref(self, ref_key: string, key:string):
self.set_value(ref_key, self.cells[key])

# repr dunder method returns output as a string
# for each key in all the cells:
# add to the output= key: and its value and return key:value pair to us
def __repr__(self):
output = "--------n"
for key in self.cells.keys():
output += f'{key}: {self.get_value(key)}n'
output += "--------"
return output

# sheet object instantiation
sheet = Sheet()
sheet.set_value('A1', 10)
sheet.set_ref('A3', 'A1') 
print(sheet) # A3 is now 10, just like A1
sheet.set_value('A1', 20)
print(sheet)  # A3 is still 10, not 20

Answer 1

假设键总是str，值总是int，你可以稍微调整一下你的代码:

class Sheet:
def __init__(self) -> None:
self.cells = dict()
# set_value method takes key as a string and value as an int, set cells with
# key index along with its value
def set_value(self, key: str, value: int) -> None:
self.cells[key] = value
# get_value method takes the key as a string and return the value of the cell
# based on key index
def get_value(self, key: str) -> int:
if type(self.cells[key]) == int:
return self.cells[key]
return self.get_value(self.cells[key])

# set ref takes new key, the reference key and the old key, the key being referenced
# use set value method to set new value that has new key and the value of the key that it references
def set_ref(self, ref_key: str, key:str):
self.set_value(ref_key, key)

# repr dunder method returns output as a string
# for each key in all the cells:
# add to the output= key: and its value and return key:value pair to us
def __repr__(self):
output = "--------n"
for key in self.cells.keys():
output += f'{key}: {self.get_value(key)}n'
output += "--------"
return output

# sheet object instantiation
sheet = Sheet()
sheet.set_value('A1', 10)
sheet.set_ref('A3', 'A1') 
print(sheet) # A3 is now 10, just like A1
sheet.set_value('A1', 20)
print(sheet)

输出:

--------
A1: 10
A3: 10
--------
--------
A1: 20
A3: 20
--------

方法签名保持不变。

我们现在设置了两种类型的值:值本身(int)或ref (str)。

秘密是当接收到值(get_value)时:我们检查值的类型;如果是int，那就是最终值。否则，使用存储在该单元格中的键递归调用get_value.