python多继承与mro_python多继承采用优先方式-优快云博客

本文链接：https://blog.youkuaiyun.com/xlisper/article/details/23712149

本文介绍了Python中两种不同的方法解析顺序：经典类的深度优先搜索和新式类的广度优先搜索，并通过具体示例展示了这两种搜索顺序的区别及其对多重继承的影响。

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1、深度优先

#!/usr/bin/env python
class Account:
	"""bank account"""
	def __init__(self, holder):
		self.balance = 0
		self.holder = holder
	def deposit(self, amount):
		self.balance = self.balance + amount
		return self.balance
	def withdraw(self, amount):
		if amount > self.balance:
			return 'not enough money!'
		return self.balance - amount

class RemoteAccount(Account):
	"""docstring for RemoteAccount"""
	deposit_charge = 1
	def __init__(self, holder):
		super(RemoteAccount, self).__init__(holder)
	def deposit(self, amount):
		return Account.deposit(self, amount - self.deposit_charge)

class InterbankAccount(Account):
	"""docstring for InterbankAccount"""
	withdraw_charge = 1
	def __init__(self, holder):
		super(InterbankAccount, self).__init__(holder)
	def withdraw(self, amount):
		return Account.withdraw(self, amount + self.withdraw_charge)

class RemoteInterbankAccount(RemoteAccount, InterbankAccount):
	"""docstring for RemoteInterbankAccount"""
	def __init__(self, holder):
		self.holder = holder
		self.balance = 0

account = RemoteInterbankAccount('zhang3')
#print [c.__name__ for c in RemoteInterbankAccount.mro()]
print account.deposit(12)
#>>> 11
print account.withdraw(10)
#>>> 1

2、广度优先

#!/usr/bin/env python
class Account(object):
	"""bank account"""
	def __init__(self, holder):
		self.balance = 0
		self.holder = holder
	def deposit(self, amount):
		self.balance = self.balance + amount
		return self.balance
	def withdraw(self, amount):
		if amount > self.balance:
			return 'not enough money!'
		return self.balance - amount

class RemoteAccount(Account):
	"""docstring for RemoteAccount"""
	deposit_charge = 1
	def __init__(self, holder):
		super(RemoteAccount, self).__init__(holder)
	def deposit(self, amount):
		return Account.deposit(self, amount - self.deposit_charge)

class InterbankAccount(Account):
	"""docstring for InterbankAccount"""
	withdraw_charge = 1
	def __init__(self, holder):
		super(InterbankAccount, self).__init__(holder)
	def withdraw(self, amount):
		return Account.withdraw(self, amount + self.withdraw_charge)

class RemoteInterbankAccount(RemoteAccount, InterbankAccount):
	"""docstring for RemoteInterbankAccount"""
	def __init__(self, holder):
		self.holder = holder
		self.balance = 0

account = RemoteInterbankAccount('zhang3')
print [c.__name__ for c in RemoteInterbankAccount.mro()]
#>>> ['RemoteInterbankAccount', 'RemoteAccount', 'InterbankAccount', 'Account', 'object']
print account.deposit(12)
#>>> 11
print account.withdraw(10)
#>>> 0

我们通常称深度优先为classic，广度优先为new-style——基类需继承object。广度优先基于C3 Method Resolution Ordering方法，该方法对应于Python中的mro方法。多重继承是一个无法标准化的问题，每一种提供多重继承的语言都有自己的继承方式，我们只需遵循这种特定方式就可以了。