CODEWITHSUNDEEP
pythonpython-3.xoopinheritance
homocomputeris
homocomputeris

Reputation: 509

How to reuse superclass method's variables in Python 3?

I want to subclass by extending a method that always has the same first stage, say:

class Data:
    def show(self):
    #  this part is common for all subclasses
        total=10

class PrintA(Data):
    def show(self):
        Data.show(self)
        print(total)

class PrintAPlus(Data):
    def show(self):
        Data.show(self)
        print(total+10)

However, I get NameError: name a is not defined.

How to reuse total variable from the superclass's method? (The obvious one is to save it as instance's attribute, but I don't need there, actually.)

Upvotes: 1

Views: 490

Answers (1)

Copperfield
Copperfield

Reputation: 8510

the problem here is that total is only assigned inside the superclass method show, there is just a local variable. its value can't be see outside it.

to fix it you need to make it a instance attribute or return that value from there

option 1

class Data:
    def show(self):
    #  this part is common for all subclasses
        self.total = 10

class PrintA(Data):
    def show(self):
        Data.show(self)
        print(self.total)

class PrintAPlus(Data):
    def show(self):
        Data.show(self)
        print(self.total+10)

option 2

class Data:
    def show(self):
    #  this part is common for all subclasses
        return 10

class PrintA(Data):
    def show(self):
        total = Data.show(self)
        print(total)

class PrintAPlus(Data):
    def show(self):
        total = Data.show(self)
        print(total+10)

Upvotes: 2

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