Python 2 Enum Example

Question

I found this code which is supposed to illustrate how enums work. I'm aware things are differnt now in Python 3, but I want to make sense of this example. What do I need to input to get print("You chose the easy option") to execute please?

I've tried 1, Easy and Choice.Easy so far with no success.

def enum(**enums):
    return type('Enum', (), enums)

Choice = enum(Easy = 1, Medium = 2, Hard = 3)
choice = input("Enter choice: ")

if choice == Choice.Easy:
    print("You chose the easy option")
elif choice == Choice.Medium:
    print("You chose the medium option")
elif choice == Choice.Hard:
    print("You chose the hard option")
else: 
    print("You should choose one of the three levels!")

Python 2 will no longer be supported in less than one month. Do not use it. — Konrad Rudolph
– Konrad Rudolph, Commented Dec 5, 2019 at 12:35

rajvi · Accepted Answer · 2019-12-05 11:40:18Z

2

The input which user has entered is string type and in Choice it has integer. Make change:

Choice = enum(Easy = '1', Medium = '2', Hard = '3')

or

choice = int(input("Enter choice: "))

in this case you need to handle exception valueError

answered Dec 5, 2019 at 11:40

rajvi

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Comments

Ethan Furman · Accepted Answer · 2019-12-05 15:48:09Z

That example does not create an enum, just a class with some members that have integer values.

The reason it is not working in Python 3 is because in Python 2 input() evaled whatever was entered, so typing 1 actually returned an int; in Python 3 input became the same as Python 2's raw_input(), which returns strs and makes you do any necessary conversions.

In other words:

Python 2

    >>> input('give me a number: ')
    give me a number:                # enter '1' and hit <Enter>
    1                                # returns the int 1

Python 3

    >>> input('give me a number: ')
    give me a number:                # enter '1' and hit <Enter>
    '1'                              # returns the str '1'

For actual Enums, use either the stdlib enum module or the third-party aenum¹ module (which supports advanced Enum creation as well as having Python 2 support).

An actual Enum would look like this:

from enum import Enum          # or from aenum import Enum

class Choice(Enum):
    Easy = 1
    Medium = 2
    Hard = 3

and converting user input:

choice = input("Enter choice: ")
choice = Choice(int(choice))

if choice is Choice.Easy:        # NB: use `is` instead of `==` for normal enums
    ...

¹ Disclosure: I am the author of the Python stdlib Enum, the enum34 backport, and the Advanced Enumeration (aenum) library.

GIRISH kuniyal · Accepted Answer · 2019-12-05 11:41:25Z

1

This is not working because you are comparing string with integer. you can take input as integer.

choice = int(input("Enter choice: "))

answered Dec 5, 2019 at 11:41

GIRISH kuniyal

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