Add-in for input() with validation

Question

What do you think about this code? Do you have some advices and remarks for me about them? I have started learning python recently.

types = { "str": str, "int": int, "float": float, "complex": complex } def my_input(kind, msg, msg_wrong, detail): """ Add-in for input(). Performs validation of the data entered. :param kind: data type. The keys of the dictionary types. If an error occurs, a str is expected. :param msg: a welcome message, such as "Enter a number -> " :param msg_wrong: own message in case of error :param detail: detailed error description (True or False) :return: entered value with type kind """ method = types.get(kind, str) while True: try: value = method(input(msg)) break except ValueError as e: print(msg_wrong, detail * str(e)) return value msg = "-> " msg_wrong = "Error" print(my_input("int", msg, msg_wrong, False)) print(my_input("hello", msg, msg_wrong, True)) # wrong type, will str print(my_input("complex", msg, msg_wrong, True)) """ -> hi Error -> 15 15 -> some text some text -> some text 2 Error complex() arg is a malformed string -> 4-j (4-1j) """ 

Answer 1

1. Your function looks usable, useful and follows PEP8, well done.

2. Coupling types and kind together seems like a poor descision. Since functions are firstclass in Python you can just pass the function.

   This would change your functions to something like:

   my_input(int, msg, msg_wrong, False) 

   This would have the drawback that if you don't pass a valid function, then it will blow-up. But has the added benifit of allowing more types with less code.

   import datetime my_input(datetime.fromisoformat, msg, msg_wrong, False) 

   You can also fix the drawback by changing kind to an argument with a default value.

   def my_input(msg, msg_wrong, detail, kind=str) my_input(msg, msg_wrong, True) 

3. It's not immediatly clear why you would want to log only certain errors with the detail argument.

   If I were to show or silence errors I would use the logging module. I'll leave configuring the logger to you, but usage would be:

   import logging logger = logging.getLogger(__name__) logger.setLevel(logging.INFO) ... def my_input(kind, msg, msg_wrong): method = types.get(kind, str) while True: try: value = method(input(msg)) break except ValueError as e: logger.debug(e) print(msg_wrong) return value ... print(my_input("int", msg, msg_wrong)) logger.setLevel(logging.DEBUG) print(my_input("hello", msg, msg_wrong)) print(my_input("complex", msg, msg_wrong)) 

   It's not apparent to me why you'd like to log some but not other errors. If being able to change the level of different calls to my_input is of the upmost importance then it'd make more sense to me for you to pass the logging level.

   def my_input(kind, msg, msg_wrong, level=logging.DEBUG): ... logger.log(level, e) 

4. I'm not used to seeing assignment, break and then a return out of a while true loop. When I do this I only use return.

import logging logger = logging.getLogger(__name__) logger.setLevel(logging.INFO) def my_input(msg, msg_wrong, cast=str): while True: try: return cast(input(msg)) except ValueError as e: logger.debug(e) print(msg_wrong) msg = "-> " msg_wrong = "Error" print(my_input(msg, msg_wrong, int)) print(my_input(msg, msg_wrong)) print(my_input(msg, msg_wrong, complex))