Tukukkk

Very new to python and have been, as an exercise, doing a text-based version of a board game (I'm an avid board gamer).

There are obviously lots of places for the user to input something, and naturally I need to evaluate those inputs and make sure they are valid.

I learned about using a True/False check and for loops from this site (thanks!) and now that I've done them so much I was wondering if there was a better way - they get a little crazy if they are nested and I want to to my best to adhere to those Zen-like Python rules.

Here is what I mean, in a simple example, using generic code so it makes sense (not all of you may know the rules of this board game!)

The goal is to make sure the code loops until a color or "none" is given. I know this accomplishes that, i'm just wondering if there is a more streamlined way that I haven't learned yet.

colors = ["red", "green", "white", "blue", "yellow"]



for color in colors:

    print(f"You can choose {color}.")



choice = input("Which color would you choose? (input a color or 'none' : ")

checker = False



while not checker:

    if choice not in colors:

        choice = input("That's not one of your options. Choose again: ")



    elif choice == "none":

        print("You don't want a color. That's fine.")

        checker = True



    else:

        print("You chose {color}! Have fun!")

        checker = True

You could define a generic function if you find yourself repeating the same things

def prompt_for_valid_input(options):

    while True:

        print(f"You can choose one of {options}.")

        choice = input("Which would you choose? (or 'none' : ")

        if choice == "none" and "none" not in options:

            print("You didn't pick anything. That's fine.")

            return None

        elif choice in options:

            return choice

        else:

            print("That's not one of your options. Choose again. ")



colors = ["red", "green", "white", "blue", "yellow"]

color = prompt_for_valid_input(colors)

if color is not None:

    print(f"You chose {color}! Have fun!")



numbers = [1, 10, 100]

num = prompt_for_valid_input(numbers)

if num is not None:

    print(f"You chose {num}! Have fun!")

So "without a while/for loop", not really. Without a sentinel variable, yes, if the conditions are simple enough.

you can abstract it out to a generic validated input method

def validated_input(prompt,validation_method,error_message):

    while True:

         result = input(prompt)

         if validation_method(result):

            return result

         print(error_message)





choices = ['red','green','blue','none']

validator = lambda test:test.lower().strip() in choices

prompt = "Enter A Color(one of Red, Green, Blue, or None):"

error_message = "Please enter a valid color or None!"



print(validated_input(prompt,validator,error_message))

its arguable whether this is "better"

Usually how you wrote your code is considered pretty "normal" and straightforward which is good. The issue is that you would want the looping part of your code to repeat till it has met its expectation. So a conditional looping event is necessary. If you really want you can simplify it a little by making a break statement for example:

x = 0

while True:

  if x == 12:

     break;

  else:

     x = x + 1

print(x)

This will create a infinite loop until the condition you are looking for is met and then it will break out of the loop. Make sure you have your escape condition though.