cs61a lab06
class Cat:
def __init__(self, name, owner, lives=9):
self.is_alive = True
self.name = name
self.owner = owner
self.lives = lives
def talk(self):
return self.name + ' says meow!'
class NoisyCat(Cat):
"""
>>> my_cat = NoisyCat("Furball", "James")
>>> my_cat.name
'Furball'
>>> my_cat.is_alive
True
>>> my_cat.lives
8
>>> my_cat.talk()
'Furball says meow! Furball says meow!'
>>> friend_cat = NoisyCat("Tabby", "James", 2)
>>> friend_cat.talk()
'Tabby says meow! Tabby says meow!'
>>> friend_cat.lives
1
"""
def __init__(self, name, owner, lives=9):
super().__init__(name,owner,lives)
self.lives -= 1
def talk(self):
words = super().talk()
words = words + " " + words
return words
类方法相关
class Dog:
dogbook = {'黄色':30, '黑色':20, '白色':0}
def __init__(self, name, color, weight):
self.name = name
self.color = color
self.weight = weight
def bark(self):
print(f'{self.name} 叫了起来')
@classmethod
def dog_num(cls):
num = 0
for v in cls.dogbook.values():
num = num + v
return num
@staticmethod
def total_weights(dogs):
total = 0
for o in dogs:
total = total + o.weight
return total
print(f'共有 {Dog.dog_num()} 条狗')
d1 = Dog('大黄', '黄色', 10)
d1.bark()
print(f'共有 {d1.dog_num()} 条狗')
d2 = Dog('旺财', '黑色', 8)
d2.bark()
print(f'狗共重 {Dog.total_weights([d1, d2])} 公斤')
'''
这个是关于Cat那道题的classmethod
'''
向上整型和向下调用
class Car:
num_wheels = 4
gas = 30
headlights = 2
size = 'Tiny'
def __init__(self, make, model):
self.make = make
self.model = model
self.color = 'No color yet. You need to paint me.'
self.wheels = Car.num_wheels
self.gas = Car.gas
def paint(self, color):
self.color = color
return self.make + ' ' + self.model + ' is now ' + color
def drive(self):
if self.wheels < Car.num_wheels or self.gas <= 0:
return 'Cannot drive!'
self.gas -= 10
return self.make + ' ' + self.model + ' goes vroom!'
def pop_tire(self):
if self.wheels > 0:
self.wheels -= 1
def fill_gas(self):
self.gas += 20
return 'Gas level: ' + str(self.gas)
class MonsterTruck(Car):
size = 'Monster'
def rev(self):
print('Vroom! This Monster Truck is huge!')
def drive(self):
self.rev()
return super().drive()
'''
子类可以调用父类方法，但父类类型声明无法调用子类方法，因为编译时没有这个函数方法
'''
classmethod
class Cat:
def __init__(self, name, owner, lives=9):
self.is_alive = True
self.name = name
self.owner = owner
self.lives = lives
def talk(self):
return self.name + ' says meow!'
@classmethod
def adopt_a_cat(cls, owner):
"""
Returns a new instance of a Cat.
This instance's owner is the given owner.
Its name and its number of lives is chosen programatically
based on the spec's noted behavior.
>>> cat1 = Cat.adopt_a_cat("Ifeoma")
>>> isinstance(cat1, Cat)
True
>>> cat1.owner
'Ifeoma'
>>> cat1.name
'Felix'
>>> cat1.lives
11
>>> cat2 = Cat.adopt_a_cat("Ay")
>>> cat2.owner
'Ay'
>>> cat2.name
'Grumpy'
>>> cat2.lives
8
"""
cat_names = ["Felix", "Bugs", "Grumpy"]
name = cat_names[len(owner) % len(cat_names)]
num_lives = len(name) + len(owner)
return cls(name,owner,num_lives)
'''
cls是类，return cls()，相当于用类初始化实例
'''
class Account:
"""An account has a balance and a holder.
>>> a = Account('John')
>>> a.deposit(10)
10
>>> a.balance
10
>>> a.interest
0.02
>>> a.time_to_retire(10.25) # 10 -> 10.2 -> 10.404
2
>>> a.balance # balance should not change
10
>>> a.time_to_retire(11) # 10 -> 10.2 -> ... -> 11.040808032
5
>>> a.time_to_retire(100)
117
"""
max_withdrawal = 10
interest = 0.02
def __init__(self, account_holder):
self.balance = 0
self.holder = account_holder
def deposit(self, amount):
self.balance = self.balance + amount
return self.balance
def withdraw(self, amount):
if amount > self.balance:
return "Insufficient funds"
if amount > self.max_withdrawal:
return "Can't withdraw that amount"
self.balance = self.balance - amount
return self.balance
def time_to_retire(self, amount):
"""Return the number of years until balance would grow to amount."""
assert self.balance > 0 and amount > 0 and self.interest > 0
n = 0
future = self.balance
while future < amount:
future += future * self.interest
n += 1
return n
'''
这题比较简单，主要是self.balance这个变量要保持不变，因此新置一个future变量
'''
class FreeChecking(Account):
"""A bank account that charges for withdrawals, but the first two are free!
>>> ch = FreeChecking('Jack')
>>> ch.balance = 20
>>> ch.withdraw(100) # First one's free
'Insufficient funds'
>>> ch.withdraw(3) # And the second
17
>>> ch.balance
17
>>> ch.withdraw(3) # Ok, two free withdrawals is enough
13
>>> ch.withdraw(3)
9
>>> ch2 = FreeChecking('John')
>>> ch2.balance = 10
>>> ch2.withdraw(3) # No fee
7
>>> ch.withdraw(3) # ch still charges a fee
5
>>> ch.withdraw(5) # Not enough to cover fee + withdraw
'Insufficient funds'
"""
withdraw_fee = 1
free_withdrawals = 2
def withdraw(self, amount):
self.free_withdrawals -= 1
if self.free_withdrawals >= 0:
return super().withdraw(amount)
return super().withdraw(amount + self.withdraw_fee)
'''
已有的方法用super().method()调用
类变量可以绑定到任意实例的method里引用
比如上面的withdraw_fee = 1
free_withdrawals =2
'''
