Question

I’d like to know where the __setitem__ and __getitem__code of pythons list type is defined. I know the list is implemented in C, but I can’t find the code implementing the indexing and slicing operations of lists.

Answer 1

You’ll find everything in the listobject.c file.

It’s methods are enumerated in the list_methods() structure. You may also want to study the PyList_Type structure for further pointers to implementations of various hooks.

Since __getitem__ and __setitem__ are part of both the C sequence protocol, the PyList_Type structure points to a new structure list_as_sequence that defines those hooks, listed in the tp_as_sequence slot of PyList_Type.

The list_item function implements the __getitem__ hook, and __setitem__ is represented by list_ass_item.

Slices, on the other hand, are handled by the mapping protocol, and you’ll end up (via list_as_mapping) at list_subscript and list_ass_subscript.