Python class @property RecursionError

Question

I want to have @property named image that when if its exist just return it simply otherwise I do some stuff and then assign it to a variable and then return it.

class MyClass:

    def __init__(self, name: str):
        self.name = name

    @property
    def image(self):
        if self.image: 
            return self.image
        # Some code
        self.image = 'image url'
        return self.image

Error message:

in image 
if self.image: return self.image
[Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Answer 1

You can't use self.image in itself, it will call the function that you are working on. This is because by defining that function with @property , when you try to access the property myClassObj.image , it will actually work by calling your function image() . So when you access self.image inside, this is where the recursion is occurring.

TL;DR : Don't access self.image inside the image function.

Have the actual image stored as self._image or something like that:

class MyClass:

    def __init__(self, name: str):
        self.name = name

    @property
    def image(self):
        if self._image: 
            return self._image
        # Some code
        self._image = 'image url'
        return self._image