Python Traceback and NameError

Question

I'm very new to programming. I've been trying to learn Python via a book called "Python Programming for the Absolute Beginner". I'm working on classes. I've copied some code from one of the exercises in the book and get a Traceback (most recent call last): and NameError message. Below are the error messages I get along with the code. Please help. Thanks!

Traceback (most recent call last):
 File "C:\Python27\Ch8 Critter Caretaker Prg.py", line 5, in <module>
   class Critter(object):
 File "C:\Python27\Ch8 Critter Caretaker Prg.py", line 25, in Critter
   mood = property(__get_mood)
NameError: name '_Critter__get_mood' is not defined

# Critter Caretaker
# A virtual pet to care for

class Critter(object):
"""A virtual pet"""
    def __init__(self, name, hunger = 0, boredom = 0):
        self.name = name
        self.hunger = hunger
        self.boredom = boredom
    def __pass_time(self):
        self.hunger += 1
        self.bordedom += 1
    def __get_mode(self):
        unhappiness = self.hunger + self.boredom
        if unhappiness < 5:
            mood = "happy"
        elif 5 <= unhappiness <= 10:
            mood = "okay"
        elif 11 <= unhappiness <= 15:
            mood = "frustrated"
        else:
            mood = "mad"

    mood = property(__get_mood)

    def talk(self):
        print "I'm", self.name, "and I feel", self.mood, "now.\n"
        self.__pass_time()

    def eat(self, food = 4):
        print "Brrupp.  Thank you."
        self.hunger -= food
        if self.hunger < 0:
            self.hunger = 0
        self.__pass_time()

    def play(self, fun = 4):
        print "Wheee!"
        self.boredom -= fun
        if self.boredom < 0:
            self.boredom = 0
        self.__pass_time()

def main():
    crit_name = raw_input("What do you want to name your critter?: ")
    crit = Critter(crit_name)

    choice = None
    while choice != "0":
        print \
        """
        Critter Caretaker

        0 - Quit
        1 - Listen to your critter
        2 - Feed your critter
        3 - Play with your critter
        """

        choice = raw_input("Choice: ")
        print

        # exit
        if choice == "0":
            print "Good-bye."

        # listen to your critter
        elif choice == "1":
            crit.talk()

        # feed your critter
        elif choice == "2":
            crit.eat()

        # play with your critter
        elif choice == "3":
            crit.play()

        # some unknown choie
        else:
            print "\nSorry, but", choice, "isn't a vaild choice."

main()
("\n\nPress the enter key to exit.")

If this book recommends the usage of leading double underscores then handle it with care. Is there any explanation why the code does not use only one underscore ? — Matthias, Nov 11 '12 at 21:34

score 2 · Answer 1 · answered Nov 11 '12 at 21:21

As already mentioned, you made a typo between mode and mood. However, you'll hit more problems later - your __get_mood function never actually gets the mood, as it never returns. Also, you can use property as a decorator:

@property
def mood(self):
    unhappiness = self.hunger + self.boredom
    if unhappiness < 5:
        return "happy"
    elif 5 <= unhappiness <= 10:
        return "okay"
    elif 11 <= unhappiness <= 15:
        return "frustrated"
    else:
        return "mad"

score 1 · Answer 2 · edited May 23 '17 at 12:33

1

It looks like you intended to define __get_mode(self) as __get_mood(self) instead.

To give some clarification about the NameError you are getting, the interpreter says that _Critter__get_mood is not defined rather than __get_mood is not defined because of name mangling, which is some Python fanciness to indicate private variables or methods in a class.

edited May 23 '17 at 12:33

Community

1
1

answered Nov 11 '12 at 21:23

kevintodisco

5,061
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score 0 · Answer 3 · answered Nov 11 '12 at 21:20

0

It's a simple typo. You define

def __get_mode(self):
#          ^^^

but access

_Critter__get_mood
#              ^^^

answered Nov 11 '12 at 21:20

phihag

278,196
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Python Traceback and NameError

3 Answers3