Is An Element of a Sequence an Object?

[Steven D'Aprano]

On Sun, 04 Jun 2017 02:15:33 +0000, Grant Edwards wrote:

> On 2017-06-03, Thomas Jollans <tjol at tjol.eu> wrote:
>> On 03/06/17 21:10, Jon Forrest wrote:
>>
>>> I'm learning about Python. A book I'm reading about it says "... a
>>> string in Python is a sequence. A sequence is an ordered collection of
>>> objects". This implies that each character in a string is itself an
>>> object.
> 
> You can think about it that way if you want, and from observable
> behavior you can't tell whether or not it's true.

Actually you can, and you recognise that yourself:

[...]
>> No, strings don't internally store the characters as objects,
> 
> Not in CPython, they don't.  In some other (hypothetical)
> implementation, they could be.  The memory usage speed implications of
> such a decision are not pleasant to contemplate.

Python strings would use a lot more memory if they were implemented in 
the way the mystery book suggests they are (each character being 
represented as a distinct object).

In Python 3, for example:


>>> import sys
>>> sys.getsizeof("abcde")  # actual memory consumption
54
>>> sum(sys.getsizeof(c) for c in "acbde")  # theoretical
250


So we can tell the two implementations apart.



-- 
Steve