Question

I’m trying to better understand the proper usage of the __str__ function.
Let’s say I have a very simple class called Character for use in a game that looks like this:

class Character(object):
""" A game character. """
def __init__(self, name):
    self.name = name
    self.poisoned = False
    self.strength = random.randrange(10, 20)
    self.max_strength = self.strength
    self.dexterity = random.randrange(10, 20)
    self.max_dexterity = self.dexterity
    self.hit_points = 100
    self.spell_points = 100
    self.weapon = []
    self.spell = []
    self.items = []
    self.aura = []
    self.xp = 0

Prior to learning about the __str__ function, I would have defined a method of the class called print_stats(self) that would print the character stats via Character.print_stats(). After learning about __str__ though it seemed like this was a function for defining and displaying the statistics of an object, similar to what I would do with print_stats(self)… but in playing with it and learning that the returned value must be a string and not contain integers, it appears my assumption is wrong.

So now my question is what are some examples of good usage of the __str__? Would the example I provide benefit from using that function?

Answer 1

Printing stats is a fine use of __str__(). Simply use string formatting to return a single string value:

def __str__(self):
    return ('Name: {name}\n'
        'Poisoned: {poisoned}\n'
        # etc.
    ).format(**self.__dict__)