How to change class instance?-CodePudding

This is my Class, below i made two instances h1 and h2, each has different names, then i want to add h2 to h1 like h1.money h2.money then we supposed to get h1.money = 100. but i dunno how to do that.

class Bank:
    def __init__(self, name):
        self.name = name
        self.money = 50

    def __add__(self, other):
        if isinstance(other, Bank):
            self.money = self.money   other.money
            return Bank(self.name)

    def info(self):
        print(self.money)


h1 = Bank('Br1')
h2 = Bank('Br2')
h1 = h1   h2

print(h1.name, h1.money)

output: Br1 50

CodePudding user response：

After you modify the money, you should return self.

class Bank:
    def __init__(self, name):
        self.name = name
        self.money = 50

    def __add__(self, other):
        if isinstance(other, Bank):
            self.money = self.money   other.money
            # return Bank(self.name)
            return self

    def info(self):
        print(self.money)


h1 = Bank('Br1')
h2 = Bank('Br2')
h1 = h1   h2

print(h1.name, h1.money)
# Br1 100

CodePudding user response：

Bank.__init__ should take an additional argument to let you set the initial value.

class Bank:
    def __init__(self, name, money=50):
        self.name = name
        self.money = money

    def __add__(self, other):
        if isinstance(other, Bank):
            money = self.money   other.money
            return Bank(self.name, money)
        return NotImplemented

    def info(self):
        print(self.money)

NotImplemented is returned when other is not an instance of Bank so that other.__radd__ gets a chance to define the operation. In general, __add__ should not modify either of its arguments (but see below).

You might also consider whether when (or if) it makes sense to add two Bank instances together. For example, what if the two Banks you are adding have different names; do you really want to just take the first one's name, ignoring the second?

Finally, if you really want to modify a bank in-place as suggested by your original code, implement Bank.__iadd__ as well:

def __iadd__(self, other):
    if isinstance(other, Bank):
        self.money  = other.money
        return self
    return NotImplemented

Then

h1  = h2  # h1.__iadd__(h2)