Re: [Twisted-Python] Help implement protocol

7 Aug 2006


      On Sat, Aug 05, 2006 at 11:44:44AM +0800, Keith Cheung (張國良) wrote:
...
Hi all,
I want to implement some handshake protocol, say..
1. Client:	WhatDate
2. Server: 	5Aug
3. Client:	WhatYear
4. Server:	2006
5. Client:	WhatTime
6. Server:	1005
So, for the client:-  (pseudo code)
  def connectionMade():
      send "WhatDate"
      state = askingForDate
  def lineReceived(data):
      switch state:
      	askingForDate:
      		date = data
      		send "WhatYear"
      		state = askingForYear
      		break
      	askingForYear:
      		year = data
      		send = "WhatTime"
      		state = askingForTime
      		break
      	askingForTime:
      		time = data
      		state = initialState
      		disconnect
The switch case becomes gigantic as the protocol grow.  Instead of keeping states, are there better ways to implement?
Twisted code often uses dynamic method dispatch to methods with prefixed names
like this:

    def connectionMade(self):
        self.sendLine('WhatDate')
        self.state = 'askingForDate'

    def lineReceived(self, line):
        handler = getattr(self, 'state_' + self.state)
        handler(line)

    def state_askingForDate(self, line):
        self.date = line
        self.sendLine('WhatYear')
        self.state = 'askingForYear'

    ...

-Andrew.

Re: [Twisted-Python] Help implement protocol

Andrew Bennetts