Object-oriented programming (python)

Question

class Ammo(Thing):
 def __init__(self, name, weapon, quantity):
 self.name=name
 self.weapon=weapon
 self.quantity=quantity
 def get_quantity(self):
 return self.quantity
 def weapon_type(self):
 return self.weapon
 def remove_all():
 self.quantity=0
bow = Weapon('bow', 10, 20)
arrows = Ammo('arrow', bow, 5)
print(arrows.weapon_type())

output of print(arrows.weapon_type()) is supposed to be bow but I got <__main__.Weapon object at 0x10441f0b8> instead. How can I modify my code so that it returns bow?

Below is class Weapon:

import random
class Weapon(Thing):
 def __init__(self, name, min_dmg, max_dmg):
 self.name=name
 self.min_dmg=min_dmg
 self.max_dmg=max_dmg
 def min_damage(self):
 return self.min_dmg
 def max_damage(self):
 return self.max_dmg
 def damage(self):
 return random.randint(self.min_dmg,self.max_dmg)

• gen_Eric: Try return self.weapon.name inside weapon_type. You are returning (and then printing) the entire Weapon object instead of just the name.
• Yang: Possible duplicate of How to print a class or objects of class using print()?
• elle: @RocketHazmat this worked perfect! Thanks!

Answer 1

I think the best way to do it would be overriding the str function in Weapon.

adding:

def __str__(self):
 return self.name

to your weapon class should fix it.

Answer 2

It depends on what do you want to print.

bow = Weapon('bow', 10, 20)
arrows = Ammo('arrow', bow, 5)
print(arrows.weapon_type())

The name of object:

bow = Weapon('bow', 10, 20)
# \_______ name of object

so you have to:

print(arrows.weapon_type().name)
# it will print bow

or your object itself:

bow = Weapon('bow', 10, 20)
# \____________________ object

I personally prefer print the name I passed in arguments, so if I call my object bow and pass "hardened_bow", 10, 20 as arguments it will print "hardened_bow" and not "bow"

Answer 3

Add repr to Weapon class:

def __repr__(self):
 return self.name

object.__repr__(self)

Called by the repr() built-in function and by string conversions (reverse quotes) to compute the "official" string representation of an object. If at all possible, this should look like a valid Python expression that could be used to recreate an object with the same value (given an appropriate environment).

If this is not possible, a string of the form <...some useful description...> should be returned. The return value must be a string object. If a class defines repr() but not str(), then repr() is also used when an "informal" string representation of instances of that class is required.

This is typically used for debugging, so it is important that the representation is information-rich and unambiguous.

object.__str__(self)

Called by the str() built-in function and by the print statement to compute the "informal" string representation of an object. This differs from __repr__() in that it does not have to be a valid Python expression: a more convenient or concise representation may be used instead. The return value must be a string object.

Reference