Synopsis - Cross-Reference

 1#
 2# Copyright (C) 2003 Stefan Seefeld
 3# All rights reserved.
 4# Licensed to the public under the terms of the GNU LGPL (>= 2),
 5# see the file COPYING for details.
 6#
 7
 8from __future__ import generators
 9from Processor import Error
10import sys
11
12class CommandLineError(Error): pass
13
14def parse_option(arg):
15    """The required format is '--option[=[arg]]' or 'option=arg'.
16    In the former case the optional argument is interpreted as
17    a string (only '--option' sets the value to True, '--option='
18    sets it to the empty string), in the latter case the argument
19    is evaluated as a python expression.
20    Returns (None, None) for non-option argument"""
21
22    if arg.find('=') == -1 and not arg.startswith('--'):
23        return None, None # we are done
24    attribute = arg.split('=', 1)
25    if len(attribute) == 2:
26        name, value = attribute
27        if name.startswith('--'):
28            name = name[2:] # value is a string
29        else:
30            try:
31                value = eval(value) # it's a python expression
32            except:
33                sys.stderr.write("""an error occured trying to evaluate the value of \'%s\' (\'%s\')
34to pass this as a string, please use %s="'%s'" \n"""%(name, value, name, value))
35                sys.exit(-1)
36    else:
37        name, value = attribute[0][2:], True # flag the attribute as 'set'
38
39    return name, value
40
41
42def get_options(args, parse_arg = parse_option, expect_non_options = True):
43    """provide an iterator over the options in args.
44    All found options are stripped, such that args will
45    contain the remainder, i.e. non-option arguments.
46    Pass each argument to the parse_option function to
47    extract the (name,value) pair. Returns as soon as
48    the first non-option argument was detected.
49    """
50
51    while args:
52        name, value = parse_arg(args[0])
53        if name:
54            args[:] = args[1:]
55            yield name, value
56        elif not expect_non_options:
57            raise CommandLineError("expected option, got '%s'"%args[0])
58        else:
59            return
60
61

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