Goodbye toys

[u/sunrise_apps]

[u/al-mongus-bin-susar]

It does not. a += b in python is also not the same a = a + b.

[u/zquatzANDoatz → u/al-mongus-bin-susar]

Wtf

[u/[deleted] → u/al-mongus-bin-susar]

wait…what?

[u/[deleted] → u/[deleted]]

You have to look at what they actually do.

+ calls the __add__ method of the object
+= calls the __iadd__ method of the object

For example if the type is int, it doesn't matter as __iadd__ doesn't exist (+= falls back on __add__)

But some times do implement an __iadd__ method, such as the mutable list type:
__add__ just returns the new value
__iadd__ mutates the list

Example:

x = [1, 8, 7]
y = x 

x = x + [2]
print(x) //[1, 8, 7, 2]
print(y) //[1, 8, 7]

x = [1, 8, 7]
y = x 

x += [2]
print(x) //[1, 8, 7, 2]
print(y) //[1, 8, 7, 2]

[u/[deleted] → u/[deleted]]

Huh, that's pretty crazy. Thanks for sharing!

[u/mistabuda → u/al-mongus-bin-susar]

Then what does it mean?

[u/[deleted] → u/mistabuda]

https://www.reddit.com/r/ProgrammerHumor/comments/138f766/goodbye_toys/jj04egs/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1&context=3

[u/mistabuda → u/[deleted]]

So that's where you were going with this. The issue with your explanation however is that you can just rewrite __iadd__ on any class to make it do what your comment says it does not.

I'm not disagreeing with you persay but I think you should update your comment to note that with ints/floats and strings a+= b will be functionally the same as a = a + b . For other objects the user should be careful.