Comment by bee_rider

Comment by bee_rider 3 days ago

Python lists aren’t arrays, right? They are the closest thing in Python to an array maybe, but they do a ton of stuff under the hood, like grow when needed.

Calling them arrays would be very confusing to everybody who expects a typical array: a pointer with some empty space after it.

Sn3llius 3 days ago

Most languages have arrays that grow automatically. I'd say C/C++ is the exception there.

When I said array, I specifically meant O(1) access, which is in contrast to linked lists, which the name "list" would seem to imply.

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pjmlp 3 days ago

C++ has them on the standard library, I would make a clear split with C in this regard.

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Phrodo_00 3 days ago

Yeah and no? Python Lists indeed don't make any sort of array-like guarantee, but they're implemented as a vector/autogrowing-array of python object references (but these objects are not guaranteed to be cache-local).

The implementation defines the underlying data structure as PyObject *ob_item

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Sn3llius 3 days ago

List access is O(1), which effectively makes them arrays :)

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- Phrodo_00 3 days ago
  
  Maybe if you don't consider CPU architecture, but most would expect to be able to do loops over Arrays that don't incur in a lot of cache misses, and Python Lists don't do that, since they're actually arrays of pointers to heap memory.
  
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