Python 开关函数

Question

我一直在尝试使用 if 构建的简单开关函数来编写一个简单的端口扫描器。我已经在这里搜索了关于如何使开关功能像在 C++ 或类似语言中一样可用的适当解决方案。我发现这里已经讨论了这个问题 Replacements for switch statement in Python?我已经尝试了其中的一些方法，但到目前为止还没有运气让它正常运行。无论我从链接中选择什么方法，我总是会在第二个 switch case 上遇到这样的语法错误:

  File "/home/h4v0kkx0008c/Desktop/Sources/setup/PortScannerV1.py", line 44
if case(2):
          ^
SyntaxError: invalid syntax

这可能是什么问题？

这是我到目前为止写的完整代码:

from socket import *
import time, socket, os, sys, string, argparse, logging, math

n = raw_input("Choose Port range: \n(1)Standard Ports: 0 - 1025\n(2)Middle Range: 1025 - 5000\n(3)Higher Range: 5000 - 49151\n(4)Highest Range: 49151 - 65535\n(5)All Ports: 0 - 65535\n(6)Custom ")

class switch(object):
    value = None
    def __new__(class_, value):
        class_.value = value
        return True

def case(*args):
    return any((arg == switch.value for arg in args))


while switch(n):



    if case(1):
        print"Your choice is: Standard Ports"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        for i in range(0, 1025):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)


    if case(2):
        print"Your choice is: Middle Range"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        for i in range(1025, 5000):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)
        break

    if case(3):
        print"Your choice is: Higher Range"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        for i in range(500, 49151):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)
        break

    if case(4):
        print"Your choice is: Highest Range"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        for i in range(49151, 65535):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)
        break

    if case(5):
        print"Your choice is: All Ports"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        for i in range(0, 65535):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)
        break

    if case(6):
        print"Your choice is: Custom"
        target= raw_input("Please specify Host or Ip to scan: ")
        targetIP = gethostbyname(target)
        print 'Starting scan on host ', targetIP
        startPort= raw_input("Specify starting Port:")
        endPort= raw_input("Specify end Port:")
        for i in range(startPort, endPort):
            s = socket(AF_INET, SOCK_STREAM)
            result = s.connect_ex((targetIP, i)
        break

Answer 1

您尝试解决此问题的方式似乎不是 pythonic。由于 python 中不存在 switch 语句，您可以使用字典模拟类似 switch 的行为，因为函数和类是 python 中的一流对象。

def func1():
    # do some operation

def func2():
    # some other operation

def default_func():
    # some default action

options = {
    '1': func1,
    '2': func2,
    'default': default_func
}

value = raw_input('enter a number')

result = options.get(int(value), options.get('default'))()

如果你的函数足够简单，你肯定可以使用lambdas作为值，这样肯定会更简洁。