23argparse

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argparse：

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習題：

實現ls命令功能，-l、-a、--all、-h選項：

顯示路徑下的文件列表；

-a和--all顯示包含.開頭的文件；

-l，詳細列表顯示；

-h和-l，人性化顯示文件大小；

c字符，d目錄，-普通文件，l軟鏈接，b塊設備，s socket文件，p pipe文件即FIFO；

按文件名排序輸出，可和ls的順序不一樣；

詳細列表顯示時，時間按“年-月-日 時:分:秒”格式顯示；

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-rw-r--r-- 1 root?? root??? 136 May? 7 09:45 test.json

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mode 硬鏈接 屬主 屬組 字節 時間 文件名

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參數分類：

ls -l /etc

位置參數，參數放在那里，就要對應一個參數位置，如/etc；

選項參數，必須通過前面是-短選項（短選項后面可以沒有參數）或--長選項，然后后面的才算它的參數，如-l；

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程序或腳本在運行時，位置參數必須寫，argparse默認的-h可有可無；

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argparse不僅僅做了參數的定義和解析，還自動幫助生成了幫助信息，尤其是usage，可以看到自定義的參數是否是自己想要的；

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源碼：

class ArgumentParser(_AttributeHolder, _ActionsContainer):

??? """Object for parsing command line strings into Python objects.

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??? Keyword Arguments:

??????? - prog -- The name of the program (default: sys.argv[0])?? #程序的名字，缺省使用sys.argv[0]

??????? - usage -- A usage message (default: auto-generated from arguments)

??????? - description -- A description of what the program does?? #為程序功能添加描述

??????? - epilog -- Text following the argument descriptions

??????? - parents -- Parsers whose arguments should be copied into this one

??????? - formatter_class -- HelpFormatter class for printing help messages

??????? - prefix_chars -- Characters that prefix optional arguments

??????? - fromfile_prefix_chars -- Characters that prefix files containing

??????????? additional arguments

??????? - argument_default -- The default value for all arguments

??????? - conflict_handler -- String indicating how to handle conflicts

??????? - add_help -- Add a -h/-help option?? #自動為解析器增加-h和--help選項，默認為True

??? """

??? def __init__(self,

???????????????? prog=None,

???????????????? usage=None,

???????????????? description=None,

???????????????? epilog=None,

???????????????? version=None,

???????????????? parents=[],

???????????????? formatter_class=HelpFormatter,

???????????????? prefix_chars='-',

???????????????? fromfile_prefix_chars=None,

? ???????????????argument_default=None,

???????????????? conflict_handler='error',

???????????????? add_help=True):

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??? def add_argument(self, *args, **kwargs):

??????? """

??????? add_argument(dest, ..., name=value, ...)

??????? add_argument(option_string, option_string, ..., name=value, ...)

??????? """

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argparse中add_argument()的action參數，內置6種動作可在解析到一個參數時進行觸發：

store_true|store_false?? #保存相應的布爾值，用于實現布爾開關

store?? #默認，保存參數值，可能會先將參數值轉換成另一個數據類型，若沒顯式指定則為默認

store_const?? #用于實現非布爾值的命令行標記，保存一個被定義為參數規格的值

append?? #將值保存到一個列表中，若參數重復出現，則保存多個值

append_const?? #將定義在參數規格中的值保存到一個列表中

version?? #打印關于程序的版本信息，然后退出

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parser = argparse.ArgumentParser(prog='ls', add_help=True, description='list directory contents')

parser.add_argument('path', nargs='?', default='.', help='path help')

# parser.add_argument('-l')

# parser.add_argument('-l', nargs='?')

parser.add_argument('-l', action='store_true', help='use a long listing format')

parser.add_argument('-a', '--all', action='store_true', help='show all files,do not ignore entries starting with .')?? #長短選項可同時給出

args = parser.parse_args()

print(args)

parser.print_help()

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例：

tests.py

import argparse

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parser = argparse.ArgumentParser()?? #獲得一個參數解析器

args = parser.parse_args()?? #分析參數

parser.print_help()?? #打印幫助

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>python tests.py -h

usage: tests.py [-h]

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optional arguments:

? -h, --help? show this help message and exit

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例：

import argparse

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parser = argparse.ArgumentParser(prog='ls', add_help=True, description='list directory contents')

parser.add_argument('path')?? #path為位置參數，必須提供，否則報error: the following arguments are required

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args = parser.parse_args()

print(args)

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s>python tests.py

usage: ls [-h] path

ls: error: the following arguments are required: path

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例：

import argparse

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parser = argparse.ArgumentParser(prog='ls', add_help=True, description='list directory contents')

parser.add_argument('path')

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args = parser.parse_args(('e:/',))?? #分析參數，同時傳入可迭代的參數，('/etc'.split())或(('/etc'),)或('/etc -all'.split())或(('/etc/','-lah'))；Namespace(path='e:/')里的path可通過Namespace對象訪問，如args.path

print(args)?? #打印名詞空間中收集的參數

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>python tests.py

Namespace(path='e:/')

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例：

import argparse

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parser = argparse.ArgumentParser(prog='ls', add_help=True, description='list directory contents')

parser.add_argument('path', nargs='?', default='.', help='path help')?? #default，給path提供默認值，當前路徑，path也變成可選的；nargs表示這個參數接收結果參數，?表示可有可無；help表示幫助文檔中這個參數的描述

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args = parser.parse_args()

print(args)

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>python tests.py

Namespace(path='.')

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-l和-a的實現：

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parser.add_argument('-l')?? #效果為

Namespace(l=None, path='.')

usage: ls [-h] [-l L] [path]

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parser.add_argument('-l', nargs='?')?? #效果為

Namespace(l=None, path='.')

usage: ls [-h] [-l [L]] [path]

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parser.add_argument('-l', action='store_true')?? #效果為

Namespace(l=False, path='.')

usage: ls [-h] [-l] [path]

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例：

parser = argparse.ArgumentParser(prog='ls', add_help=False, description='list directory contents')

parser.add_argument('path', nargs='?', default='.', help='path help')

parser.add_argument('-l', action='store_true', help='use a long listing format')

parser.add_argument('-a', '--all', action='store_true', help='show all files,do not ignore entries starting with .')

parser.add_argument('-h', action='store_true', help='making readable easily')

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if __name__ == '__main__':

??? args = parser.parse_args()

??? print('args=', args)

??? # parser.print_help()

??? print(args.path, args.l, args.h, args.all)

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>python tests.py -l -a .

args= Namespace(all=True, h=False, l=True, path='.')

. True False True

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版本1：

import argparse

from pathlib import Path

import datetime

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import win_unicode_console

win_unicode_console.enable()

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def _convert_mode(mode: int):

??? modelst = ['r', 'w', 'x', 'r', 'w', 'x', 'r', 'w', 'x']?? #modelst = list('rwx'*3)

??? modestr = bin(mode)[-9:]

??? # print(modestr)

??? ret = ''

??? for i, c in enumerate(modestr):

??????? if c == '1':

??????????? ret += modelst[i]

??????? else:

??????????? ret += '-'

??? return ret

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def _convert_human(size: int):

??? # units =? [' ', 'K', 'M', 'G', 'T', 'P']?? # units = list(' KMGTP')

??? units = ' KMGTP'

??? depth = 0

??? while size >= 1000:

??????? size = size // 1000

??????? depth += 1

??? return '{}{}'.format(size, units[depth])

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def _convert_type(file:Path):

??? ret = ''

??? if file.is_dir():

??????? ret = 'd'

??? elif file.is_symlink():

??????? ret = 'l'

??? elif file.is_socket():

??????? ret = 's'

??? elif file.is_block_device():

??????? ret = 'b'

??? elif file.is_char_device():

??????? ret = 'c'

??? else:

??????? ret = '-'

??? return ret

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def showdir(path: str='.', detail=False, all=False, human=False) -> list:

??? p = Path(path)

??? for file in p.iterdir():

??????? # if not all:

??????? #???? if file.name.startswith('.'):

??????? #???????? continue

??????? if not all and file.name.startswith('.'):

??????????????? continue

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??????? if detail:

??????????? st = file.stat()

????????? ??# print(st)?? #os.stat_result(st_mode=33206, st_ino=7599824371282335, st_dev=178462745, st_nlink=1, st_uid=0, st_gid=0, st_size=47, st_atime=1551941978, st_mtime=1551941978, st_ctime=1551928586)

??????????? h = str(st.st_size)

??????????? if human:

???? ???????????h = _convert_human(st.st_size)

??????????? # drwxr-xr-x 9 ane? ane? 4.0K Apr 11 02:40 apache-tomcat-7.0.67

??????????? # (33206, 1, 0, 0, 3031, 1557296696.6941395, 'tests.py')

??????????? # yield (st.st_mode, st.st_nlink, st.st_uid, st.st_gid, st.st_size, st.st_atime, file.name)

??????????? yield (_convert_type(file) + _convert_mode(st.st_mode), st.st_nlink, st.st_uid, st.st_gid, h,

?????????????????? datetime.datetime.fromtimestamp(st.st_atime).strftime('%Y-%m-%d %H:%M:%S'), file.name)

??????? else:

??????? # print(file.name)

??????????? yield file.name

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# print(showdir.__annotations__)

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parser = argparse.ArgumentParser(prog='ls', add_help=False, description='list directory contents')

parser.add_argument('path', nargs='?', default='.', help='path help')

parser.add_argument('-l', action='store_true', help='use a long listing format')

parser.add_argument('-a', '--all', action='store_true', help='show all files,do not ignore entries starting with .')

parser.add_argument('-h', action='store_true', help='making readable easily')

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if __name__ == '__main__':

??? args = parser.parse_args()

??? print('args=', args)

??? # parser.print_help()

??? print('path={} -l={} -h={} -a={}'.format(args.path, args.l, args.h, args.all))

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??? for file in showdir(args.path, detail=args.l, all=args.all, human=args.h):

??????? print(file)

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版本2：

1、使用stat模塊，

In [29]: help(stat.filemode)

Help on built-in function filemode in module _stat:

filemode(...)

??? Convert a file's mode to a string of the form '-rwxrwxrwx'

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In [24]: p = Path('gis.log')

In [25]: p.stat

Out[25]: <bound method Path.stat of WindowsPath('gis.log')>

In [26]: p.stat()

Out[26]: os.stat_result(st_mode=33206, st_ino=1970324837080203, st_dev=178462745, st_nlink=1, st_uid=0, st_gid=0, st_size=70330, st_atime=1550905696, st_mtime=1550905642, st_ctime=1550905696)

In [27]: p.stat().st_mode

Out[27]: 33206

In [28]: stat.filemode(p.stat().st_mode)

Out[28]: '-rw-rw-rw-'

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2、整合代碼，用到yield from；

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import argparse

from pathlib import Path

import datetime

import stat

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import win_unicode_console

win_unicode_console.enable()

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parser = argparse.ArgumentParser(prog='ls', add_help=False, description='list directory contents')

parser.add_argument('path', nargs='?', default='.', help='path help')

parser.add_argument('-l', action='store_true', help='use a long listing format')

parser.add_argument('-a', '--all', action='store_true', help='show all files,do not ignore entries starting with .')

parser.add_argument('-h', action='store_true', help='making readable easily')

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def showdir(path: str='.',? detail=False, all=False, human=False) -> list:

??? # modelst = ['r', 'w', 'x', 'r', 'w', 'x', 'r', 'w', 'x']? # modelst = list('rwx'*3)

??? # def _convert_mode(mode: int):

??? #???? modestr = bin(mode)[-9:]

??? #???? # print(modestr)

??? #???? ret = ''

??? #???? for i, c in enumerate(modestr):

??? #???????? if c == '1':

??? #???????????? ret += modelst[i]

??? #???????? else:

??? #???????????? ret += '-'

??? #???? return ret

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??? def _convert_human(size: int):

??????? # units =? [' ', 'K', 'M', 'G', 'T', 'P']?? # units = list(' KMGTP')

??????? units = ' KMGTP'

??????? depth = 0

??????? while size >= 1000:

??????????? size = size // 1000

??????????? depth += 1

??????? return '{}{}'.format(size, units[depth])

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??? # def _convert_type(file:Path):

??? #???? ret = ''

??? #???? if file.is_dir():

??? #???????? ret = 'd'

??? #???? elif file.is_symlink():

??? #???????? ret = 'l'

??? #???? elif file.is_socket():

??? #???????? ret = 's'

??? #???? elif file.is_block_device():

??? #???????? ret = 'b'

??? #???? elif file.is_char_device():

??? #???????? ret = 'c'

??? #???? else:

??? #???????? ret = '-'

??? #???? return ret

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??? def _showdir(path: str='.', detail=False, all=False, human=False) -> list:

??????? p = Path(path)

??????? for file in p.iterdir():

??????????? # if not all:

??????????? #???? if file.name.startswith('.'):

??????????? #???????? continue

??????????? if not all and file.name.startswith('.'):

??????????????????? continue

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??????????? if detail:

??????????????? st = file.stat()

??????????????? # print(st)?? #os.stat_result(st_mode=33206, st_ino=7599824371282335, st_dev=178462745, st_nlink=1, st_uid=0, st_gid=0, st_size=47, st_atime=1551941978, st_mtime=1551941978, st_ctime=1551928586)

??????????????? h = str(st.st_size)

??????????????? if human:

??????????????????? h = _convert_human(st.st_size)

??????????????? # drwxr-xr-x 9 ane? ane? 4.0K Apr 11 02:40 apache-tomcat-7.0.67

??????????????? # (33206, 1, 0, 0, 3031, 1557296696.6941395, 'tests.py')

??????????????? # yield (st.st_mode, st.st_nlink, st.st_uid, st.st_gid, st.st_size, st.st_atime, file.name)

??????????????? # yield (_convert_type(file) + _convert_mode(st.st_mode), st.st_nlink, st.st_uid, st.st_gid, h,

?????????????????????? # datetime.datetime.fromtimestamp(st.st_atime).strftime('%Y-%m-%d %H:%M:%S'), file.name)

??????????????? yield (stat.filemode(st.st_mode), st.st_nlink, st.st_uid, st.st_gid, h,

?????????????????????? datetime.datetime.fromtimestamp(st.st_atime).strftime('%Y-%m-%d %H:%M:%S'), file.name)

??????????? else:

??????????? # print(file.name)

??????????????? yield file.name

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??? yield from sorted(_showdir(path, detail, all, human), key=lambda x: x[len(x)-1])

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# print(showdir.__annotations__)

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if __name__ == '__main__':

??? args = parser.parse_args()

??? print('args=', args)

??? # parser.print_help()

??? print('path={} -l={} -h={} -a={}'.format(args.path, args.l, args.h, args.all))

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??? for file in showdir(args.path, detail=args.l, all=args.all, human=args.h):

??????? print(file)

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>python tests.py -lah .

args= Namespace(all=True, h=True, l=True, path='.')

path=. -l=True -h=True -a=True

('-rw-rw-rw-', 1, 0, 0, '47 ', '2019-03-07 14:59:38', '__init__.py')

('drwxrwxrwx', 1, 0, 0, '4K', '2019-04-02 17:15:21', '__pycache__')

('-rw-rw-rw-', 1, 0, 0, '209 ', '2019-03-07 14:42:00', 'admin.py')

('-rw-rw-rw-', 1, 0, 0, '1K', '2019-04-01 13:36:40', 'adminx.py')

('-rw-rw-rw-', 1, 0, 0, '119 ', '2019-03-07 14:59:03', 'apps.py')

('-rw-rw-rw-', 1, 0, 0, '854 ', '2019-03-27 15:12:48', 'forms.py')

('drwxrwxrwx', 1, 0, 0, '4K', '2019-03-07 13:46:16', 'migrations')

('-rw-rw-rw-', 1, 0, 0, '2K', '2019-03-28 16:32:33', 'models.py')

('-rw-rw-rw-', 1, 0, 0, '4K', '2019-05-08 16:05:48', 'tests.py')

('-rw-rw-rw-', 1, 0, 0, '786 ', '2019-03-28 16:10:02', 'urls.py')

('-rw-rw-rw-', 1, 0, 0, '9K', '2019-03-30 15:48:10', 'views.py')