使用click创建完美的Python命令行程序

def encrypt(plaintext, key):cyphertext = ''for character in plaintext:if character.isalpha():number = ord(character)number += keyif character.isupper():if number &gt; ord('Z'):number -= 26elif number  ord('z'):number -= 26elif number <h3>初学者方法：sys.argv</h3><p>脚本需要先获取命令行参数的值，让我们先用最简单的sys.argv实现。</p><p>sys.argv是一个列表，包含了用户在运行脚本时输入的所有参数（包括脚本名字本身）。</p><p>在终端输入以下指令：</p><p></p><pre class="brush:python;toolbar:false;">&gt; python caesar_script.py --key 23 --decrypt my secret messagepb vhfuhw phvvdjh

['caesar_script.py', '--key', '23', '--decrypt', 'my', 'secret', 'message']

import sysfrom caesar_encryption import encrypdef caesar():key = 1is_error = Falsefor index, arg in enumerate(sys.argv):if arg in ['--key', '-k'] and len(sys.argv) &gt; index + 1:key = int(sys.argv[index + 1])del sys.argv[index]del sys.argv[index]breakfor index, arg in enumerate(sys.argv):if arg in ['--encrypt', '-e']:del sys.argv[index]breakif arg in ['--decrypt', '-d']:key = -keydel sys.argv[index]breakif len(sys.argv) == 1:is_error = Trueelse:for arg in sys.argv:if arg.startswith('-'):is_error = Trueif is_error:print(f'Usage: python {sys.argv[0]} [ --key <key> ] [ --encrypt|decrypt ] <text>')else:print(encrypt(' '.join(sys.argv[1:]), key))if __name__ == '__main__':caesar()</text></key>

&gt; python caesar_script_using_sys_argv.pyUsage: python caesar.py [ --key <key> ] [ --encrypt|decrypt ] <text></text></key>

import argparsefrom caesar_encryption import encryptdef caesar():parser = argparse.ArgumentParser()group = parser.add_mutually_exclusive_group()group.add_argument('-e', '--encrypt', action='store_true')group.add_argument('-d', '--decrypt', action='store_true')parser.add_argument('text', nargs='*')parser.add_argument('-k', '--key', type=int, default=1)args = parser.parse_args()text_string = ' '.join(args.text)key = args.keyif args.decrypt:key = -keycyphertext = encrypt(text_string, key)print(cyphertext)if __name__ == '__main__':caesar()

> python caesar_script_using_argparse.py --encode My messageusage: caesar_script_using_argparse.py [-h] [-e | -d] [-k KEY] [text [text ...]]caesar_script_using_argparse.py: error: unrecognized arguments: --encode> python caesar_script_using_argparse.py --helpusage: caesar_script_using_argparse.py [-h] [-e | -d] [-k KEY] [text [text ...]]positional arguments:textoptional arguments:-h, --help show this help message and exit-e, --encrypt-d, --decrypt-k KEY, --key KEY

import clickfrom caesar_encryption import encrypt@click.command()@click.argument('text', nargs=-1)@click.option('--decrypt/--encrypt', '-d/-e')@click.option('--key', '-k', default=1)def caesar(text, decrypt, key):text_string = ' '.join(text)if decrypt:key = -keycyphertext = encrypt(text_string, key)click.echo(cyphertext)if __name__ == '__main__':caesar()

import clickfrom caesar_encryption import encrypt@click.command()@click.option('--input_file',type=click.File('r'),help='File in which there is the text you want to encrypt/decrypt.' 'If not provided, a prompt will allow you to type the input text.',)@click.option('--output_file',type=click.File('w'),help='File in which the encrypted / decrypted text will be written.' 'If not provided, the output text will just be printed.',)@click.option('--decrypt/--encrypt','-d/-e',help='Whether you want to encrypt the input text or decrypt it.')@click.option('--key','-k',default=1,help='The numeric key to use for the caesar encryption / decryption.')def caesar(input_file, output_file, decrypt, key):if input_file:text = input_file.read()else:text = click.prompt('Enter a text', hide_input=not decrypt)if decrypt:key = -keycyphertext = encrypt(text, key)if output_file:output_file.write(cyphertext)else:click.echo(cyphertext)if __name__ == '__main__':caesar()

> python caesar_script_v2.py --helpUsage: caesar_script_v2.py [OPTIONS]Options:--input_file FILENAMEFile in which there is the text you want to encrypt/decrypt. If not provided, a prompt will allow you to type the input text.--output_file FILENAME File in which the encrypted/decrypted text will be written. If not provided, the output text will just be printed.-d, --decrypt / -e, --encryptWhether you want to encrypt the input text or decrypt it.-k, --key INTEGERThe numeric key to use for the caesar encryption / decryption.--help Show this message and exit.

> python caesar_script_v2.py --decrypt --input_file wrong_file.txtUsage: caesar_script_v2.py [OPTIONS]Error: Invalid value for "--input_file": Could not open file: wrong_file.txt: No such file or directory

> python caesar_script_v2.py --encrypt --key 2Enter a text: **************yyy.ukectc.eqo

import clickimport enchantfrom caesar_encryption import encrypt@click.command()@click.option('--input_file',type=click.File('r'),required=True,)@click.option('--output_file',type=click.File('w'),required=True,)def caesar_breaker(input_file, output_file):cyphertext = input_file.read()english_dictionnary = enchant.Dict("en_US")max_number_of_english_words = 0for key in range(26):plaintext = encrypt(cyphertext, -key)number_of_english_words = 0for word in plaintext.split(' '):if word and english_dictionnary.check(word):number_of_english_words += 1if number_of_english_words > max_number_of_english_words:max_number_of_english_words = number_of_english_wordsbest_plaintext = plaintextbest_key = keyclick.echo(f'The most likely encryption key is {best_key}. It gives the following plaintext:nn{best_plaintext[:1000]}...')output_file.write(best_plaintext)if __name__ == '__main__':caesar_breaker()

import clickimport enchantfrom tqdm import tqdmfrom caesar_encryption import encrypt@click.command()@click.option('--input_file',type=click.File('r'),required=True,)@click.option('--output_file',type=click.File('w'),required=True,)def caesar_breaker(input_file, output_file):cyphertext = input_file.read()english_dictionnary = enchant.Dict("en_US")best_number_of_english_words = 0for key in tqdm(range(26)):plaintext = encrypt(cyphertext, -key)number_of_english_words = 0for word in plaintext.split(' '):if word and english_dictionnary.check(word):number_of_english_words += 1if number_of_english_words > best_number_of_english_words:best_number_of_english_words = number_of_english_wordsbest_plaintext = plaintextbest_key = keyclick.echo(f'The most likely encryption key is {best_key}. It gives the following plaintext:nn{best_plaintext[:1000]}...')output_file.write(best_plaintext)if __name__ == '__main__':caesar_breaker()