Initialize ArgParse with a Json config file

argparse_configreader.py

import argparse
import os
import json

class ArgParseConfigurationReader(object):
    """
    Example of config JSON : 
    {
    "description": "Program",
    "args": [
        { "short": "geoname_input", "help": "Filepath of the Geonames file you want to use." },
        { "short": "-v", "long": "--verbose", "action": "store_true" },
        { "short": "-n", "long": "--ngram-size", "type": "int", "default": 2 },
        { "short": "-t", "long": "--tolerance-value", "type": "float", "default": 0.002 },
        { "short": "-e", "long": "--epochs", "type": "int", "default": 100 },
        { "short": "-m", "long": "--model", "choices": ["CNN", "LSTM"], "default": "CNN" }
        ]
    }
    """
    def __init__(self,configuration_file):
        if not os.path.exists(configuration_file):
            raise FileNotFoundError("'{0} file could not be found ! '".format(configuration_file))

        self.configuration = json.load(open(configuration_file))

        self.__argparser_desc = ("" if not "description" in self.configuration else self.configuration["description"])
        self.parser = argparse.ArgumentParser(description=self.__argparser_desc)

        self.parse_conf()
    
    def parse_conf(self):
        if not "args" in self.configuration:
            raise argparse.ArgumentError("","No args given in the configuration file")
        
        for dict_args in self.configuration["args"]:
            if not isinstance(dict_args,dict):
                raise ValueError("Args must be dictionnary")

            short_command = dict_args.get("short",None)
            long_command = dict_args.get("long",None)
            
            if not short_command and not long_command:
                raise ValueError("No command name was given !") 
            
            add_func_dict_= {}
            if "help" in dict_args:
                add_func_dict_["help"]= dict_args["help"]
            if "default" in dict_args:
                add_func_dict_["default"]= dict_args["default"]
            if "action" in dict_args:
                add_func_dict_["action"]= dict_args["action"]
            if "type" in dict_args:
                add_func_dict_["type"]= eval(dict_args["type"])
            if "choices" in dict_args:
                add_func_dict_["choices"]= dict_args["choices"]

            if not (short_command and long_command):
                command = (short_command if not long_command else long_command)
                self.parser.add_argument(command,**add_func_dict_)

            elif long_command and short_command:
                self.parser.add_argument(short_command,long_command,**add_func_dict_)
    
    def parse_args(self,input_=None):
        if not input_:
            return self.parser.parse_args()
        return self.parser.parse_args(input_)