"getopt" --- C-style parser for command line options
****************************************************

**ソースコード:** Lib/getopt.py

注釈:

  This module is considered feature complete. A more declarative and
  extensible alternative to this API is provided in the "optparse"
  module. Further functional enhancements for command line parameter
  processing are provided either as third party modules on PyPI, or
  else as features in the "argparse" module.

======================================================================

This module helps scripts to parse the command line arguments in
"sys.argv". It supports the same conventions as the Unix "getopt()"
function (including the special meanings of arguments of the form
'"-"' and '"--"').  Long options similar to those supported by GNU
software may be used as well via an optional third argument.

Users who are unfamiliar with the Unix "getopt()" function should
consider using the "argparse" module instead. Users who are familiar
with the Unix "getopt()" function, but would like to get equivalent
behavior while writing less code and getting better help and error
messages should consider using the "optparse" module. See Choosing an
argument parsing library for additional details.

このモジュールは2つの関数と1つの例外を提供しています:

getopt.getopt(args, shortopts, longopts=[])

   Parses command line options and parameter list.  *args* is the
   argument list to be parsed, without the leading reference to the
   running program. Typically, this means "sys.argv[1:]". *shortopts*
   is the string of option letters that the script wants to recognize,
   with options that require an argument followed by a colon ("':'";
   i.e., the same format that Unix "getopt()" uses).

   注釈:

     Unlike GNU "getopt()", after a non-option argument, all further
     arguments are considered also non-options. This is similar to the
     way non-GNU Unix systems work.

   *longopts* は長形式のオプションの名前を示す文字列のリストです。名前
   には、先頭の "'--'" は含めません。引数が必要な場合には名前の最後に
   等号 ("'='") を入れます。オプション引数はサポートしていません。長形
   式のオプションだけを受けつけるためには、*shortopts* は空文字列であ
   る必要があります。長形式のオプションは、該当するオプションを一意に
   決定できる長さまで入力されていれば認識されます。たとえば、
   *longopts* が "['foo', 'frob']" の場合、"--fo" は "--foo" にマッチ
   しますが、"--f" では一意に決定できないので、"GetoptError" が送出さ
   れます。

   返り値は2つの要素から成っています: 最初は "(option, value)" のタプ
   ルのリスト、2つ目はオプションリストを取り除いたあとに残ったプログラ
   ムの引数リストです (*args* の末尾部分のスライスになります)。それぞ
   れの引数と値のタプルの最初の要素は、短形式の時はハイフン 1つで始ま
   る文字列 (例: "'-x'")、長形式の時はハイフン2つで始まる文字列 (例:
   "'--long-option'") となり、引数が2番目の要素になります。引数をとら
   ない場合には空文字列が入ります。オプションは見つかった順に並んでい
   て、複数回同じオプションを指定できます。長形式と短形式のオプション
   は混在できます。

getopt.gnu_getopt(args, shortopts, longopts=[])

   この関数はデフォルトで GNU スタイルのスキャンモードを使う以外は
   "getopt()" と同じように動作します。つまり、オプションとオプションで
   ない引数とを混在させることができます。"getopt()" 関数はオプションで
   ない引数を見つけると解析を停止します。

   If the first character of the option string is "'+'", or if the
   environment variable "POSIXLY_CORRECT" is set, then option
   processing stops as soon as a non-option argument is encountered.

exception getopt.GetoptError

   This is raised when an unrecognized option is found in the argument
   list or when an option requiring an argument is given none. The
   argument to the exception is a string indicating the cause of the
   error.  For long options, an argument given to an option which does
   not require one will also cause this exception to be raised.  The
   attributes "msg" and "opt" give the error message and related
   option; if there is no specific option to which the exception
   relates, "opt" is an empty string.

exception getopt.error

   "GetoptError" へのエイリアスです。後方互換性のために残されています
   。

Unix スタイルのオプションを使った例です:

   >>> import getopt
   >>> args = '-a -b -cfoo -d bar a1 a2'.split()
   >>> args
   ['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
   >>> optlist, args = getopt.getopt(args, 'abc:d:')
   >>> optlist
   [('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
   >>> args
   ['a1', 'a2']

長形式のオプションを使っても同様です:

   >>> s = '--condition=foo --testing --output-file abc.def -x a1 a2'
   >>> args = s.split()
   >>> args
   ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
   >>> optlist, args = getopt.getopt(args, 'x', [
   ...     'condition=', 'output-file=', 'testing'])
   >>> optlist
   [('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x', '')]
   >>> args
   ['a1', 'a2']

In a script, typical usage is something like this:

   import getopt, sys

   def main():
       try:
           opts, args = getopt.getopt(sys.argv[1:], "ho:v", ["help", "output="])
       except getopt.GetoptError as err:
           # print help information and exit:
           print(err)  # will print something like "option -a not recognized"
           usage()
           sys.exit(2)
       output = None
       verbose = False
       for o, a in opts:
           if o == "-v":
               verbose = True
           elif o in ("-h", "--help"):
               usage()
               sys.exit()
           elif o in ("-o", "--output"):
               output = a
           else:
               assert False, "unhandled option"
       process(args, output=output, verbose=verbose)

   if __name__ == "__main__":
       main()

Note that an equivalent command line interface could be produced with
less code and more informative help and error messages by using the
"optparse" module:

   import optparse

   if __name__ == '__main__':
       parser = optparse.OptionParser()
       parser.add_option('-o', '--output')
       parser.add_option('-v', dest='verbose', action='store_true')
       opts, args = parser.parse_args()
       process(args, output=opts.output, verbose=opts.verbose)

A roughly equivalent command line interface for this case can also be
produced by using the "argparse" module:

   import argparse

   if __name__ == '__main__':
       parser = argparse.ArgumentParser()
       parser.add_argument('-o', '--output')
       parser.add_argument('-v', dest='verbose', action='store_true')
       parser.add_argument('rest', nargs='*')
       args = parser.parse_args()
       process(args.rest, output=args.output, verbose=args.verbose)

See Choosing an argument parsing library for details on how the
"argparse" version of this code differs in behaviour from the
"optparse" (and "getopt") version.

参考:

  Module "optparse"
     Declarative command line option parsing.

  "argparse" モジュール
     More opinionated command line option and argument parsing
     library.
