increment of a class attribute everytime an object is created-CodePudding

I would like to know how to increase/increment an attribute of a class.

I have a class called Account which has an attribute: self.code which is initialized at 0 and I want each time that an object is created the attribute increases.

so, for example:

account1=Account()
account2=Account()
account3=Account()

if I do account3.code I want to have 3 as a result. Is there a possible way to do so? thank you in advance.

CodePudding user response：

you can do it like this:

class Example:
    code = 0

    def __new__(cls, *args, **kwargs):
        cls.code  = 1
        return super().__new__(Example, *args, **kwargs)

    def __del__(self):
        cls.code -= 1


ex1 = Example()
print(ex1.code) # 1
ex2 = Example()
print(ex2.code) # 2
ex3 = Example()
print(ex3.code) # 3

CodePudding user response：

If you also want each Account instance to store the code at which it was created you can use it like this

class Account:
    last_code = 0
    def __init__(self) -> None:
        self.code = Account.last_code   1
        Account.last_code = self.code

a = Account()
b = Account()
c = Account()

print(a.code) # 1
print(b.code) # 2
print(c.code) # 3

CodePudding user response：

You can define a static variable for the Account object and increment it everytime you create a new object like this:

class Account:
    code = 0
    self.id = 0
    def __init__(self):
        self.id = Account.code
        Account.code  = 1
    def __del__(self):
        Account.code -= 1

The code variable defines how many instances were created. Every account has an id