Regarding __iter__ Magic Method in Python OOP

Question

https://code.sololearn.com/c2n4UI9P4GE4/?ref=app

This is the code with which I'm having some problem.
The problem is the 10th line, why it is causing a TypeError? Whereas the 8th line is working fine. Aren't both of them supposed to perform the same task?

It would be very nice of you if you helps me.

Answer 1

def __iter__(self):
for item in self.itbl:
yield item

obj = Demolist([1,2,3])

x = iter(obj)
for n in x:
print(n)

Answer 2

I think it's this:
You're missing the __next__() method. (in python2 just next())

This might help:

https://stackoverflow.com/questions/40923522/JUMP_LINK__&&__python__&&__JUMP_LINK-defining-an-iterator-class-failed-with-iter-returned-non-iterator-of

If that doesn't help check this out:

https://help.semmle.com/wiki/display/PYTHON/__iter__+method+returns+a+non-iterator

I hope any of those help!

Answer 3

Check this two codes, you will maybe understand how to use iter function!
__iter__ must return an iterator.

Example :
Liste = list(range(10))
iterable = iter(Liste) #returns iterator
print(next(iterable)) #outputs 0
print(next(iterable)) #outputs 1
#... Etc

So there is is another magic method __next__

https://code.sololearn.com/cAIE9Q5eaxzX/?ref=app
https://code.sololearn.com/cVNgGs49bku3/?ref=app

Answer 4

Anna we can do :
def __iter__(self) :
yield from self.itbl

Answer 5

Anna
Paul Grasser
Théophile

Thank you

Answer 6

Now, I got this, the 10th is causing a TypeError because an object isn't a suitable type for that iter() function.

Answer 7

i find oop in python extremely confusing :(

Answer 8

HydrationDash
In start I was too but now I'm okay with it.
And sololearn's explanation on some topics isn't wide enough to understand all the concepts more and more clearly.
I prefer you to study OOP with YouTube and from some other websites alongside with SL.

Answer 9

Abdul Samad thanks! :D