Method chaining in python results in an error

Question

I thought in Python I am allowed to perform method chaining.

basket = [1,3,2,4,6,8]

basket.append(7)
basket.sort()
basket.reverse()

This works.

basket.append(7).sort().reverse()

This does not.

AttributeError: 'NoneType' object has no attribute 'sort'

I am not sure what is going on here, but I assume that happens because in place methods result in "NoneType" result = basket.sort() and therefore the second method will be performed on the result and not the original object.

Can anyone help me how to do these operations without writing a new line for each method?

Answer 1

Because append sort and reverse are all "in-place" methods, so they don't return anything, instead they update the original list, the best way would be:

print(sorted(basket + [7], reverse=True))