We don't have tuple comprehensions, and this proposal isn't to add them,
so this post is edging into off-topic for the thread so feel free to
skip it.
On Sat, Oct 16, 2021 at 03:18:20PM -0400, David Mertz, Ph.D. wrote:
> Rather, I'm concerned with readability and programmer expectations. Tuples
> are best used as "records" of heterogeneous but structured data. This is
> what makes namedtuples such an elegant extension. When I see a collection
> of tuples, I generally expect each to have the same "shape", such as a
> string at index 0, a float at index 1, and an int at index 2. If those
> positions have attribute names, so much the better.
>
> In contrast, lists (and iterators) I expect to contain many things that are
> "the same" in a duck-type way. I usually want to loop through them and
> perform the same operation on each (maybe with some switches, but in the
> same block).
Right-o, the old "heterogeneous tuples versus homogeneous lists"
distinction, I remember that from the old 1.5 days. I haven't heard it
mentioned for a long time!
That certainly remains a reasonable guideline to make, albeit less so
today:
- for structured data, today we have other options such as named tuples
(rather than anonymous builtin tuples), SimpleNamespace and
Dataclasses, which may be considered closer matches to "record" or
"struct" types from other languages;
- lists and tuples now share the same Sequence interface;
- which now justifies treating tuples as "frozen lists", or lists as
"mutable tuples".
But I note that this distinction doesn't make unpacking less useful.
Here's an example. Suppose I have two data types represented by
coordinates, as tuples:
* a point is a 2-tuple (x, y)
* a rectangle is a 4-tuple (left, top, right, bottom).
Then I can construct a rectangle from the coordinates of the top-left
and bottom-right points:
rect = (*topleft, *bottomright)
> Having a million such similar items is commonplace. Having a million
> *fields* is non-existent.
I will grant you that having a million items in a tuple is *unusual*,
but it takes more than that to make something an anti-pattern. To be an
anti-pattern, something must be commonly used as a solution to some
problem, while actually being ineffective or counter-productive.
https://en.wikipedia.org/wiki/Anti-pattern
--
Steve
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/HI2WZR2MYGL4J4EY4OIVZGIRZ5CZVV4Z/
Code of Conduct: http://python.org/psf/codeofconduct/
