Is An Element of a Sequence an Object?

[Akira Li]

Jon Forrest <nobozo at gmail.com> writes:

> I'm learning about Python. A book I'm reading about it
> says "...
> a string in Python is a sequence.

correct.

> A sequence is an ordered collection of objects".

correct. https://docs.python.org/3/glossary.html#term-sequence

> This implies that each character in a string
> is itself an object.

Everything in Python is an object. If *s* is a name that refers to a str
object then *s[i]* returns i-th Unicode code point from the string as a
str object of length 1:

  >>> s = "ab"
  >>> s[0]
  'a'

It does not matter how *s* is represented internally on a chosen Python
implementation: *s[0]* may return an existing object or it may create a
new one on-the-fly.

Here's a perfectly valid sequence of ten squares:

  >>> class Squares:
  ...     def __getitem__(self, i):
  ...         if not (-len(self) <= i < len(self)):
  ...             raise IndexError(i)
  ...         if i < 0:
  ...             i += len(self)
  ...         return i * i
  ...
  ...     def __len__(self):
  ...         return 10
  >>> s = Squares()
  >>> s[9]
  81

All 10 squares are generated on-the-fly (though all int objects already
exist due to the small int caching on CPython).