title: CS61A-Object
date: 2024-01-30 11:42:48
tags: Study

17-Generator

Yield

  • 用yield代替return，可以返回多次
  • 返回值是一个iterator
#yield from
for x in a:
	yield a
# 等价于
yield from a
  • 获得一个单词中的所有字串
def prefixes(s):
	if s:
	yield from prefixer(s[:-1])
	yield s

def substrings(s):
	if s:
		yield from prefisxes(s)
		yield from substrings(s[1:])

Example: partitions

def partitions(n, m):
	if n>0 and m>0:
		if n==m:
			yield str(m)
		for p in partiotions(n-m, m):
			yield p+'+'+str(m)
		yield from partitions(n, m-1)

18/19-Object/Attribute

Class

calss <name>:
	name = XXX
	def dance():
		return XXX
	...
	<suite> #attributes
  • 使用__init__初始化class
  • self: A new instance of the class in create #相当于一张等待书写的白纸
class Account:
	def __init__(self, account_holder): #Constructor
		self.balance = 0 
		self.holder = account_holder

Attribute

  • 类中的attribute值改变，所有实例的值跟着改变
  • class中为function，instance中为method

Ant

  • 以类造类
  • 将父类属性和函数传递给子类（用下面的函数继承）
class FireAnt(Ant):
or
class LongThrower(ThrowerAnt)
  • 父类继承 (继承父类属性，或将变量传递给父类构造函数)
  • super() 用于多重继承，当有多个继承出现时使用
class Chidren(Partents):
	def __init__ (self, value):
		super.__init__(value)