Returning value when calling instance python

Question

I was wondering how to achieve this behavior.

When you call a variable in python, it directly displays some value.

like:

>> a= 5
>> a
5

libraries like numpy also do this

>> a = np.array([1,2])
>> a
>> array([1,2])

Happens something like that right? So i want to emulate that behaviour to build a class

class example(object):
   def __init__(self,intputs):
       self.out = inputs
...
instance = example(inputs)

such that when i write

instance

it were directly equivalent to do

instance.out

Cos the most similar thing I know is setting call to do that but in that case it would be calling instance() with those brackets

The interactive shell (i.e. the REPL) is actually what's printing the value, not the Python interpreter. — Jonah Bishop, Nov 09 '18 at 20:37

score 0 · Answer 1 · answered Nov 09 '18 at 20:57

I'm not exactly sure why you want to do this. The proper way to handle printing out the value of a class instance is to provide either a __str__ or __repr__ method for your class (depending on what exactly you want to see), call that method, and print the result. For most cases, a simple __str__ call will suffice:

class example(object):
    def __init__(self,intputs):
        # your init code here

    def __str__(self):
        # construct a string for the class value and return it
        return str(self.some_value)

You would then do something like the following to get the string representation in your code:

instance = example(some_value)
print(str(instance))

Here's a helpful article and relevant SO question on the difference between __str__ and __repr__.

Returning value when calling instance python

1 Answers1