Subversion Repositories programming

#!/usr/bin/env python

#

# Copyright 2006, Ira W. Snyder (devel@irasnyder.com)

# License: GNU GPL v2 (or, at your option, any later version)

#

# Print structure description:

# ===============================================

# desc = { TYPE1 : func1, TYPE2 : func2, ... }

#

# Each type will be a unique key (enforced by the dict)

# Each func will be a pointer to a function.

import errno

class PrintSystem (object):

	"""A very generic printing system. This class allows you to specify a

	   structure that describes your printing system, and it will handle

	   any further messages sent to it."""

	def __init__ (self, description):

		self.__description = description

	def __default_action (self, mytype, mydata):

		print 'ERROR: no action for: type=%s data=%s' % (str(mytype), str(mydata))

	def mprint (self, message):

		"""Print a message according to our description.

		   It should be in the form (TYPE, ...)"""

		# If there is no type in the message, it must be invalid

		if len(message) < 1:

			return -errno.EINVAL

		mytype = message[0]  # the first element is the type

		mydata = message[1:] # the rest is the data

		# If we don't have a valid function to use, this message

		# must be invalid

		if mytype not in self.__description.keys():

			self.__default_action (mytype, mydata)

			return -errno.EINVAL

		# Looks like we're good, call the correct function

		# with the data given

		try:

			self.__description[mytype](mydata)

		except:

			print 'Had an exception while trying to print what appeared to'

			print 'be a valid message. The message was:'

			self.__default_action (mytype, mydata)

			return -errno.EINVAL

		# We got here, so we completed successfully!

		return 0

################################################################################

# Test material is below

################################################################################

def f1 (data):

	(a, b, c) = data

	print 'in f1 a=%d b=%d c=%d' % (a, b, c)

def f2 (data):

	(a, b) = data

	print 'in f2 a=%s b=%s' % (a, b)

def f3 (data):

	print 'no data for f3'

def main():

	( TYPE1, TYPE2, TYPE3 ) = range(3)

	mystruct = { TYPE1 : f1, TYPE2 : f2, TYPE3 : f3 }

	ps = PrintSystem (mystruct)

	print 'All here should succeed:'

	ps.mprint ((TYPE1, 1, 2, 3))

	ps.mprint ((TYPE2, 'hello', 'world'))

	ps.mprint ((TYPE3,))

	ps.mprint ((TYPE1, 2, 3, 4))

	print '\nShould fail here:'

	ps.mprint ((20, 'a', 'b', 'c'))

if __name__ == '__main__':

	# Run test code

	main ()