Doc/lib/libgetopt.tex

   1 \section{Standard Module \module{getopt}}
   2 \label{module-getopt}
   3 \stmodindex{getopt}
   4
   5 This module helps scripts to parse the command line arguments in
   6 \code{sys.argv}.
   7 It supports the same conventions as the \UNIX{} \cfunction{getopt()}
   8 function (including the special meanings of arguments of the form
   9 `\code{-}' and `\code{-}\code{-}').
  10 % That's to fool latex2html into leaving the two hyphens alone!
  11 Long options similar to those supported by
  12 GNU software may be used as well via an optional third argument.
  13 This module provides a single function and an exception:
  14
  15 \begin{funcdesc}{getopt}{args, options\optional{, long_options}}
  16 Parses command line options and parameter list.  \var{args} is the
  17 argument list to be parsed, without the leading reference to the
  18 running program. Typically, this means \samp{sys.argv[1:]}.
  19 \var{options} is the string of option letters that the script wants to
  20 recognize, with options that require an argument followed by a colon
  21 (i.e., the same format that \UNIX{} \cfunction{getopt()} uses).  If
  22 specified, \var{long_options} is a list of strings with the names of
  23 the long options which should be supported.  The leading
  24 \code{'-}\code{-'} characters should not be included in the option
  25 name.  Options which require an argument should be followed by an
  26 equal sign (\code{'='}).
  27
  28 The return value consists of two elements: the first is a list of
  29 \code{(\var{option}, \var{value})} pairs; the second is the list of
  30 program arguments left after the option list was stripped (this is a
  31 trailing slice of the first argument).
  32 Each option-and-value pair returned has the option as its first
  33 element, prefixed with a hyphen (e.g., \code{'-x'}), and the option
  34 argument as its second element, or an empty string if the option has
  35 no argument.
  36 The options occur in the list in the same order in which they were
  37 found, thus allowing multiple occurrences.  Long and short options may
  38 be mixed.
  39 \end{funcdesc}
  40
  41 \begin{excdesc}{error}
  42 This is raised when an unrecognized option is found in the argument
  43 list or when an option requiring an argument is given none.
  44 The argument to the exception is a string indicating the cause of the
  45 error.  For long options, an argument given to an option which does
  46 not require one will also cause this exception to be raised.
  47 \end{excdesc}
  48
  49
  50 An example using only \UNIX{} style options:
  51
  52 \begin{verbatim}
  53 >>> import getopt, string
  54 >>> args = string.split('-a -b -cfoo -d bar a1 a2')
  55 >>> args
  56 ['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
  57 >>> optlist, args = getopt.getopt(args, 'abc:d:')
  58 >>> optlist
  59 [('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
  60 >>> args
  61 ['a1', 'a2']
  62 >>>
  63 \end{verbatim}
  64
  65 Using long option names is equally easy:
  66
  67 \begin{verbatim}
  68 >>> s = '--condition=foo --testing --output-file abc.def -x a1 a2'
  69 >>> args = string.split(s)
  70 >>> args
  71 ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
  72 >>> optlist, args = getopt.getopt(args, 'x', [
  73 ...     'condition=', 'output-file=', 'testing'])
  74 >>> optlist
  75 [('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x',
  76  '')]
  77 >>> args
  78 ['a1', 'a2']
  79 >>>
  80 \end{verbatim}