parser.add_argument('-i', '--integers', nargs='?', const=100, type=int, help='input a number')

import argparse

parser = argparse.ArgumentParser(description='This is a parse demo') 
parser.add_argument('-i', '--integers', nargs='?', const=10, default=100, type=int, help='input a number')

args = parser.parse_args() 
print(args.integers)

# 顯式調(diào)用
$ python t3.py  -i 1
1
# 使用const屬性
$ python t3.py  -i
10
# 使用參數(shù)的默認值
$ python t3.py
100

import argparse

parser = argparse.ArgumentParser(description='This is a parse demo') 

group1 = parser.add_argument_group('group1', 'group1 description')
group1.add_argument('--foo', help='foo help')
group1.add_argument('--foo2', help='foo1 help')
group2 = parser.add_argument_group('group2', 'group2 description')
group2.add_argument('--bar', help='bar help')
group2.add_argument('--bar2', help='bar2 help')

args = parser.parse_args() 
print(args)

# 測試
$ python t3.py -h
usage: t3.py [-h] [--foo FOO] [--foo2 FOO2] [--bar BAR] [--bar2 BAR2]

This is a parse demo

optional arguments:
  -h, --help   show this help message and exit

group1:
  group1 description

  --foo FOO    foo help
  --foo2 FOO2  foo1 help

group2:
  group2 description

  --bar BAR    bar help
  --bar2 BAR2  bar2 help

import argparse

parser = argparse.ArgumentParser(description='This is a parse demo')
group = parser.add_mutually_exclusive_group()
group.add_argument('--foo', action='store_true')
group.add_argument('--bar', action='store_false')

args = parser.parse_args()
print(args)

# 測試互斥組
$ python t3.py --foo
Namespace(foo=True, bar=True)

$ python t3.py --bar
Namespace(foo=False, bar=False)

$ python t3.py --foo --bar
usage: t3.py [-h] [--foo | --bar]
t3.py: error: argument --bar: not allowed with argument --foo

import argparse

def add(arguments):
    print(f'{arguments.x} + {arguments.y} = {arguments.x + arguments.y}')

def sub(arguments):
    print(f'{arguments.x} - {arguments.y} = {arguments.x - arguments.y}')

# create the top-level parser
parser = argparse.ArgumentParser(description='This is a parse demo') 
subparsers = parser.add_subparsers()

# create the parser for command 'add'
add_parser = subparsers.add_parser('add', help='calc add')
add_parser.add_argument('-x',  type=int, help='x value')
add_parser.add_argument('-y',  type=int, help='y value')
add_parser.set_defaults(func=add)

# create the parser for command 'sub'
sub_parser = subparsers.add_parser('sub', help='calc sub')
sub_parser.add_argument('-x',  type=int, help='x value')
sub_parser.add_argument('-y',  type=int, help='y value')
sub_parser.set_defaults(func=sub)

args = parser.parse_args() 
print(f"print the input: x={args.x}, y={args.y}")

args.func(args) # 跳轉(zhuǎn)到對應(yīng)的函數(shù)

# 測試
$ python t2.py add -x 1 -y=2
print the input: x=1, y=2
1 + 2 = 3

$ python t2.py sub -x 1 -y 2
print the input: x=1, y=2
1 - 2 = -1