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))

• Owl: What do you mean by word "cast"? I don't understand it with translation to my language. If I do how your fourth example, IDE PyCharm gives me notice "Expected type Type[str] got Type[int] instead". I add in docstring ":type cast: str, int, float, complex" (for Python 3) and notice disappears. Is it a right decision?
• Owl: Hmm.. If I write ":type cast: str, " that notice disappears too.
• Peilonrayz: @Owl Here's a Wikipedia page for more information, I'm unsure if it has been translated into your language however. In short a = 1; b = str(a) "casts" (converts) a from int to string and assigns it to b. I think using cast: Type = str would also fix the problem.