Terminology: "reference" versus "pointer"

Steven D'Aprano steve at pearwood.info
Mon Sep 14 19:03:22 CEST 2015


On Tue, 15 Sep 2015 01:10 am, Random832 wrote:

> On Mon, Sep 14, 2015, at 10:48, Akira Li wrote:
>> start, stop, step attributes (corresponding Python ints) may not exist
>> ("the objects we've talking about have never been created") until you
>> request them explicitly.
> 
> That's not true in CPython. In fact, the range object in python contains
> *four* reference boxes - one more for length.

I really don't see why any of this is relevant to the business being
discussed.

A range object is an object. It has an interface, e.g. it is sized (has a
length), it has start, stop and step attributes.

But the *implementation* of that interface is (1) irrelevant and (2) subject
to change. Maybe the __len__ method calculates the length on the fly. Maybe
start, stop and step are virtual attributes that extract the appropriate
values from a C-level datastructure inaccessible to pure Python code.

Unless you are the author of the range class, you don't really have any
business worrying about whether range.start is a "reference" to the start
value, or something computed on the fly as needed. It could be either.


-- 
Steven



More information about the Python-list mailing list