I'm still learning python so I'm still confused on what is going on when it prints "<__main__.Game object at 0x000001B55BE82B90>"

user5tpa1 0
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class Game:
    def __init__(self, lives):
        self.lives = lives
    def push(self, num):
        self.lives.append(num)
    def pop(self):
        self.lives.pop()
    def peek(self):
        print(self.lives)

I want to print lives and remove or add depending on the answer is correct by the user but it does print "<main.Game object at 0x000001B55BE82B90>"

lives =[0, 0, 0]
lives1 = Game(lives)
print(lives1)
a = 5
b = 5
c = a+b
print(a, "+" ,b, "= ")
ans = int(input("Please write the answer:"))
if (c == and):
    lives1.push(0)
else:
    lives1.pop()

print(lives1)
class function list python
1 Answers

When you create a class, the default string generated when you print an instance of the class has the form <module.class object at address>:

>>> class Example:
...     pass
...
>>> x = Example()
>>> print(x)
<__main__.Example object at 0x0000013D58E1FF10>

There are two methods you can define to make your own display of the class:

  • __repr__ defines a debug representation of the object.
  • __str__ defines a print representation of the object.

Example:

>>> class Example:
...   def __init__(self, value):
...     self.value = value
...   def __repr__(self):
...     return f'Example(value={self.value})'
...   def __str__(self):
...     return f'Value = {self.value}'
...
>>> x = Example(7)
>>> x                  # In the REPL, shows __repr__ string
Example(value=7)
>>> print(repr(x))     # repr() explicitly calls __repr__
Example(value=7)
>>> print(x)           # print uses __str__ string
Value = 7
>>> print(str(x))      # str() explicitly calls __str__
Value = 7

When defining classes, consider at least defining __repr__ so it prints useful information about the class as recommended by the __repr__ documentation:

... 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) [e.g. eval(repr(obj))] ...

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

Define __str__ if you need a "pretty" print. If __str__ is not defined, str() uses __repr__.

>>> class Game:
...     def __init__(self, lives):
...         self.lives = lives
...     def push(self, num):
...         self.lives.append(num)
...     def pop(self):
...         self.lives.pop()
...     def peek(self):
...         print(self.lives)
...     def __repr__(self):
...         return f'Game(lives={self.lives})'
...     def __str__(self):
...         return f'Lives = {self.lives}'
...
>>> g = Game([1,2,3])
>>> g
Game(lives=[1, 2, 3])
>>> print(g)
Lives = [1, 2, 3]

Note the __repr__ string I used can be evaluated to produce a Game object with the same value as recommended:

>>> g2 = eval(repr(g))
>>> g2
Game(lives=[1, 2, 3])
Mark Tolonen0
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