Yeah, spelunking around this is a great way to learn a language!
That said, “is an object” is a bit of an overloaded term in this context. Most things in Python can be semantically addressed as objects (they have fields and methods, “dir” interrogates them, and so on), but not everything is necessarily backed by the same kind of heap-allocated memory object. Some builtins and bytecode-level optimizations, similar to (but not quite the same as) the ones discussed in TFA, result in things being less object-like (that is, PyObject*-ish structs with refcounting and/or pointer chasing on field access) in some cases.
And that’s an important difference, not a nitpick! It means that performance-interested folks can’t always use the same intuition for allocation/access behavior that they do when determining what fields are available on a syntactic object.
(And before the inevitable “if you want performance don’t write Python/use native libraries” folks pipe up: people still regularly have to care about making plain Python code fast. You might wish it weren’t so, but it is.)
That said, “is an object” is a bit of an overloaded term in this context. Most things in Python can be semantically addressed as objects (they have fields and methods, “dir” interrogates them, and so on), but not everything is necessarily backed by the same kind of heap-allocated memory object. Some builtins and bytecode-level optimizations, similar to (but not quite the same as) the ones discussed in TFA, result in things being less object-like (that is, PyObject*-ish structs with refcounting and/or pointer chasing on field access) in some cases.
And that’s an important difference, not a nitpick! It means that performance-interested folks can’t always use the same intuition for allocation/access behavior that they do when determining what fields are available on a syntactic object.
(And before the inevitable “if you want performance don’t write Python/use native libraries” folks pipe up: people still regularly have to care about making plain Python code fast. You might wish it weren’t so, but it is.)