[Python] How is `self` accessed in Python methods?

I am wondering how self works under-the-hood in Python classes.

My current limited understanding is that when a class is defined, e.g.

class Foo:
def __init__(self, x: int):
self.x = x

def bar(self, a: float):
print(self.x)
print(a)


we get Foo in the current environment, and this object contains the methods attached to the class definition, in this case bar.

When we create an instance, e.g.

foo = Foo(1)


We now have both foo and Foo, the former containing the assigned fields, and the latter containing the methods.

So now when I call:

foo.bar(3.14)


a lookup to find bar is performed, first in foo.__dict__, and then, failing that, in Foo.__dict__.

Once bar is found in Foo.__dict__, it is called roughly like:

Foo.__dict__["bar"](foo, 3.14)


Is this an accurate explanation of what happens?

And if so, how is foo actually passed to the method? Is it a via a pointer to the instance?

I am a bit confused about how PyObject and PyTypeObject fit into this.

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