如何优化代码

Question

我只是在学习python，并编写了一些代码来使用库来设置iptables。我遇到的问题是，我不得不一遍又一遍地重写许多相同的代码行。我有点理解函数，但不理解OOP。我认为有一种更好的OOP方式来编写这段代码，但我无法理解它。任何指示都将受到极大的赞赏。代码在下面。

import iptc

def dropAllInbound():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    rule.in_interface = 'eth+'
    rule.target = iptc.Target(rule, 'DROP')
    chain.insert_rule(rule)

def allowLoopback():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    rule.in_interface = 'lo'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def allowEstablishedInbound():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    match = rule.create_match('state')
    match.state = 'RELATED,ESTABLISHED'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def allowHTTP():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    rule.in_interface = 'eth+'
    rule.protocol = 'tcp'
    match = rule.create_match('tcp')
    match.dport = '80'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def allowHTTPS():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    rule.in_interface = 'eth+'
    rule.protocol = 'tcp'
    match = rule.create_match('tcp')
    match.dport = '443'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def allowSSH():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    rule = iptc.Rule()
    rule.in_interface = 'eth+'
    rule.protocol = 'tcp'
    match = rule.create_match('tcp')
    match.dport = '22'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def allowEstablishedOutbound():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'OUTPUT')
    rule = iptc.Rule()
    match = rule.create_match('state')
    match.state = 'RELATED,ESTABLISHED'
    rule.target = iptc.Target(rule, 'ACCEPT')
    chain.insert_rule(rule)

def dropAllOutbound():
    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'OUTPUT')
    rule = iptc.Rule()
    rule.in_interface = 'eth+'
    rule.target = iptc.Target(rule, 'DROP')
    chain.insert_rule(rule)

def defaultAction():
    dropAllOutbound()
    dropAllInbound()
    allowLoopback()
    allowEstablishedInbound()
    allowEstablishedOutbound()

def getInput():
        print 'Default action (1) is most secure '
        print 'Default  -  1'
        print 'HTTP     -  2'
        print 'HTTPS    -  3'
        print 'SSH      -  4'
        print 'Exit     -  5'
        choices = raw_input('Enter choices (comma Separated) ').split(',')
        for action in choices:
            if action == "1":
                defaultAction()
                break
            if action == "2":
                allowHTTP()
                break
            if action == "3":
                allowHTTPS()
                break
            if action == "4":
                allowSSH()
                break
            else:
                break
getInput()

注意所有规则都有相似的代码行。是否有一种方法可以创建规则生成器对象，或者类似的方法来最小化对代码的重写？

，我这样添加了以下函数，并在每次运行脚本时调用它，以便规则被刷新.

def startClean():
    chainIn = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')
    chainIn.flush()
    chainOut = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'OUTPUT')
    chainOut.flush()

Answer 1

OOP是为了保持某物的状态。OOP是指具有属性和方法的对象来操作这些属性。

class Chair(object):

    MAX_WEIGHT = 300

    def __init__(self):
        super().__init__()

        self.weight = 5
        self.currentWeight = self.weight
        self.holding = None
        self.broken = False

    def hold(self, item):
        self.holding = item
        self.currentWeight = self.weight + item.weight
        self.checkWeight()

    def checkWeight(self):
        if self.holding.weight > self.MAX_WEIGHT:
            self.broken = True
            ...

您的代码似乎很好；仅为OOP重新编写代码可能比它更有价值。如果您真的想使用OOP，您可能希望做如下所示的事情。

class Table(object):
    def __init__(self):
        self.chain = None
        self.rule = None
        self.match = None

    def setInput(self):
        self.chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'INPUT')

    def setOutput(self):
        self.chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'OUTPUT')

    ...

table = Table()
table.setInput()
...