Python decorator example for passing command line arguments to a function

command_line_decorator.py

from utils import with_cmd_line_args

@with_cmd_line_args
def main(cmd_line):
  """ Write the contents of one file to another """
  
  with open(cmd_line.input_file) as in_file:
    with open(cmd_line.output_file, "w") as out_file:
        for line in in_file:
          out_file.write(line)

          
if __name__ == "__main__":
  main()

utils.py

import argparse

def with_cmd_line_args(f):
  """ Decorator that passes along input file path and output file path 
      command line arguments to a decorated function """
  
  def wrapper(*args, **kwargs):
    parser = argparse.ArgumentParser()
    
    # define all command line arguments, we'll just do two file paths
    parser.add_argument("-i", "--input-file", type=str, help="An input file path")
    parser.add_argument("-o", "--output-file", type=str, help="An output file path")
    
    # return the wrapped function with the parsed arguments
    return f(parser.parse_args(), *args, **kwargs)
  return wrapper