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# $Id: getoptions.py,v 1.1 2003/12/11 04:38:59 stefan Exp $
#
# Copyright (C) 2003 Stefan Seefeld
# All rights reserved.
# Licensed to the public under the terms of the GNU LGPL (>= 2),
# see the file COPYING for details.
#
from __future__ import generators
import sys
def parse_option(arg):
"""The required format is '--option[=[arg]]' or 'option=arg'.
In the former case the optional argument is interpreted as
a string (only '--option' sets the value to True, '--option='
sets it to the empty string), in the latter case the argument
is evaluated as a python expression.
Returns (None, None) for non-option argument"""
if arg.find('=') == -1 and not arg.startswith('--'):
return None, None # we are done
attribute = arg.split('=', 1)
if len(attribute) == 2:
name, value = attribute
if name.startswith('--'):
name = name[2:] # value is a string
else:
try:
value = eval(value) # it's a python expression
except:
sys.stderr.write("""an error occured trying to evaluate the value of \'%s\' (\'%s\')
to pass this as a string, please use %s="'%s'" \n"""%(name, value, name, value))
sys.exit(-1)
else:
name, value = attribute[0][2:], True # flag the attribute as 'set'
return name, value
def get_options(args, parse_arg = parse_option):
"""provide an iterator over the options in args.
All found options are stripped, such that args will
contain the remainder, i.e. non-option arguments.
Pass each argument to the parse_option function to
extract the (name,value) pair. Returns as soon as
the first non-option argument was detected.
"""
while args:
name, value = parse_arg(args[0])
if name:
args[:] = args[1:]
yield name, value
else:
return
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