Writing Help For A Script

The first thing comes to my mind about help is like this:

Executing the script with -h, then a usage is printed to Windows PowerShell.

py weather_report.py -h

So, to implement this requirement, I have two sub tasks:

1. Add a description for the script

Solution: import argparse

import argparse

# help
parser = argparse.ArgumentParser(
    description = '''
    line1
    \t* line2
    ''')
args=parser.parse_args()

And test it,

Then the new question is how to display the argparse help in multiple lines?

Solution: RawTextHelpFormatter

import argparse
# help
parser = argparse.ArgumentParser(
description = '''
这是一个查询城市天气的程序。
\t* 请输入城市或者地区的中文名称。
\t\t例子1：上海
\t\t例子2：浦东新区
\t* 退出请输入quit或者exit后按回车键，不区分大小写。
\t* 退出前会打印所有查询过的城市天气信息。
''', formatter_class = argparse.RawTextHelpFormatter)
args = parser.parse_args()

Summary: Import argparse to add help for script. By default, ArgumentParser objects line-wrap the description and epilog texts in command-line help messages.Use the RawTextHelpFormatter class instead to indicate that you already wrapped the lines.

2. How to execute a command line

How to execute "py weather_report.py -h" in python script, and get the output?

Solution: import subprocess

import subprocess

output = subprocess.check_output("py .\weather_report.py -h")

And test it, garbled text is displayed.

Solution: Decoding in 'gbk'

Summary: subprocess.check_out() run command with arguments and return its output. If the return code is non-zero, it raises a CalledProcessError. The CalledProcessError object will have the return code in returncode attribute and any output in the output attribute. By default, this function will return the data as encoded bytes.

So here is the last function: print_help()

# print help
def print_help():
    try:
        output = subprocess.check_output("py .\weather_report.py -h")
        output = output.decode("gbk")
        print("output:{0}".format(output))
    except subprocess.CalledProcessError as e:
        output = e.output
        code = e.returncode
        print(code, output)