How to update a variable linked to another variable in Python

February 3, 2022

I have the following code:

class StringIterator:

    def __init__(self, compressedString: str):
        self.compressedString = compressedString
        self.i = 0
        self.idigit = self.i +2

The problem is that the variable ‘self.idigit’ (linked to self.i) will not update if self.i changes. For example, if I increment self.i with 1 (self.i += 1), printing or returning self.idigit will not recalculate the variable (returning 1+2=3). How can I do that?

>Solution :

you can read more about property.

class StringIterator:
    def __init__(self, compressedString: str):
        self.compressedString = compressedString
        self.i = 0
        
        # self.idigit = self.i +2  # it is equal is self.idigit = 0 + 2
        # you can have a property like this

    @property
    def idigit(self):
        return self.i + 2

obj = StringIterator("Hello")
print(obj.i, obj.idigit) # 0, 2
obj.i += 1
print(obj.i, obj.idigit) # 1,3