क्लासेस — डेटा और व्यवहार एक साथ

order = {"name": "pen", "price": 15.0, "quantity": 3}

print(order["nmae"])

KeyError: 'nmae'

class OrderLine:
    def __init__(self, name, price, quantity):
        self.name = name
        self.price = price
        self.quantity = quantity

    def total(self):
        return round(self.price * self.quantity, 2)


line = OrderLine("pen", 15.0, 3)

print(line.name)
print(line.total())

pen
45.0

class OrderLine:
    def __init__(self, name):
        self.name = name

    def shout():
        return "hello"


line = OrderLine("pen")
print(line.shout())

TypeError: OrderLine.shout() takes 0 positional arguments but 1 was given

class OrderLine:
    def __init__(self, name):
        self.name = name


print(OrderLine("pen"))

<__main__.OrderLine object at 0x00000213E88A9DF0>

class OrderLine:
    def __init__(self, name, price):
        self.name = name
        self.price = price

    def __repr__(self):
        return f"OrderLine(name={self.name!r}, price={self.price!r})"


line = OrderLine("pen", 15.0)
print(line)
print([line, line])

OrderLine(name='pen', price=15.0)
[OrderLine(name='pen', price=15.0), OrderLine(name='pen', price=15.0)]

class OrderLine:
    def __init__(self, name):
        self.name = name


a = OrderLine("pen")
b = OrderLine("pen")

print(a == b)
print(a == a)

False
True

class OrderLine:
    def __init__(self, name):
        self.name = name

    def __eq__(self, other):
        return self.name == other.name


a = OrderLine("pen")
b = OrderLine("pen")

print(a == b)
print(a is b)

True
False

class Basket:
    TAX_RATE = 0.15
    items = []

    def add(self, name):
        self.items.append(name)


a = Basket()
b = Basket()
a.add("pen")
b.add("bag")

print(a.items)
print(b.items)
print(a.items is b.items)

['pen', 'bag']
['pen', 'bag']
True

class Basket:
    TAX_RATE = 0.15

    def __init__(self):
        self.items = []

    def add(self, name):
        self.items.append(name)


a = Basket()
b = Basket()
a.add("pen")
b.add("bag")

print(a.items)
print(b.items)
print(a.TAX_RATE, b.TAX_RATE)

['pen']
['bag']
0.15 0.15

"""दो छोटी कक्षाओं से बना एक ऑर्डर।"""

TAX_RATE = 0.15


class OrderLine:
    """ऑर्डर पर एक वस्तु: यह क्या है, इसकी कीमत क्या है, कितनी संख्या है।"""

    def __init__(self, name, price, quantity):
        if quantity < 1:
            raise ValueError(f"quantity must be at least 1: {quantity}")
        self.name = name
        self.price = price
        self.quantity = quantity

    def total(self):
        """टैक्स सहित इस लाइन की कीमत।"""
        return round(self.price * self.quantity * (1 + TAX_RATE), 2)

    def __repr__(self):
        return f"OrderLine({self.name!r}, {self.price!r}, {self.quantity!r})"


class Order:
    """लाइनों का एक संग्रह, और इसके बारे में पूछे जाने वाले प्रश्न।"""

    def __init__(self, customer):
        self.customer = customer
        self.lines = []

    def add(self, name, price, quantity):
        self.lines.append(OrderLine(name, price, quantity))
        return self

    def total(self):
        return round(sum(line.total() for line in self.lines), 2)

    def largest(self):
        """सबसे महंगी लाइन, या खाली ऑर्डर के लिए None।"""
        if not self.lines:
            return None
        return max(self.lines, key=lambda line: line.total())

    def __repr__(self):
        return f"Order({self.customer!r}, {len(self.lines)} lines)"


def main():
    order = Order("rafi")
    order.add("pen", 15.0, 3)
    order.add("bag", 850.0, 1)
    order.add("ink", 120.0, 2)

    for line in order.lines:
        print(f"{line.name:<6} {line.total():>9.2f}")

    print(f"{'total':<6} {order.total():>9.2f}")
    print()
    print(order)
    print("largest:", order.largest())

    try:
        order.add("clip", 5.0, 0)
    except ValueError as err:
        print("rejected:", err)


if __name__ == "__main__":
    main()

pen        51.75
bag       977.50
ink       276.00
total    1305.25

Order('rafi', 3 lines)
largest: OrderLine('bag', 850.0, 1)
rejected: quantity must be at least 1: 0