class Point:     def __init__(self, x=1.0, y=1.0):self.x = xself.y = y

class Point:     __slots__ = x, ydef __init__(self, x=1.0, y=1.0):self.x = xself.y = y

from dataclasses import dataclass@dataclass
class Point:x: float = 1.0y: float = 1.0

from collections import namedtuple

>>> Account = namedtuple('Account', ['type', 'balance'], defaults=[0]) >>> Account._field_defaults {'balance': 0}

>>> Account = namedtuple('Account', ['type', 'balance'], defaults=[0，0]) >>> Account._field_defaults{'type': 0, 'balance': 0}

EmployeeRecord = namedtuple('EmployeeRecord', 'name, age, title, department, paygrade')import csv
for emp in map(EmployeeRecord._make, csv.reader(open("employees.csv", "rb"))):print(emp.name, emp.title)import sqlite3
conn = sqlite3.connect('/companydata')
cursor = conn.cursor()
cursor.execute('SELECT name, age, title, department, paygrade FROM employees')
for emp in map(EmployeeRecord._make, cursor.fetchall()):print(emp.name, emp.title)

>>> t = [11, 22]
>>> Point._make(t)
Point(x=11, y=22)>>> p = Point(x=11, y=22)
>>> p._asdict()
OrderedDict([('x', 11), ('y', 22)])>>> p = Point(x=11, y=22)
>>> p._replace(x=33)
Point(x=33, y=22)
>>> for partnum, record in inventory.items():
...     inventory[partnum] = record._replace(price=newprices[partnum], timestamp=time.now())>>> p._fields            # view the field names
('x', 'y')
>>> Color = namedtuple('Color', 'red green blue')
>>> Pixel = namedtuple('Pixel', Point._fields + Color._fields)
>>> Pixel(11, 22, 128, 255, 0)
Pixel(x=11, y=22, red=128, green=255, blue=0)>>> getattr(p, 'x')
11>>> class Point(namedtuple('Point', ['x', 'y'])):
...     __slots__ = ()
...     @property
...     def hypot(self):
...         return (self.x ** 2 + self.y ** 2) ** 0.5
...     def __str__(self):
...         return 'Point: x=%6.3f  y=%6.3f  hypot=%6.3f' % (self.x, self.y, self.hypot)
>>> for p in Point(3, 4), Point(14, 5/7):
...     print(p)
Point: x= 3.000  y= 4.000  hypot= 5.000
Point: x=14.000  y= 0.714  hypot=14.018>>> Point3D = namedtuple('Point3D', Point._fields + ('z',))>>> Book = namedtuple('Book', ['id', 'title', 'authors'])
>>> Book.__doc__ += ': Hardcover book in active collection'
>>> Book.id.__doc__ = '13-digit ISBN'
>>> Book.title.__doc__ = 'Title of first printing'
>>> Book.authors.__doc__ = 'List of authors sorted by last name'>>> Account = namedtuple('Account', 'owner balance transaction_count')
>>> default_account = Account('<owner name>', 0.0, 0)
>>> johns_account = default_account._replace(owner='John')
>>> janes_account = default_account._replace(owner='Jane')