Hi Guido,
If a C++ function already has a return value, plus some primitive
pointer variables that need to be moved into the result in Python,
then we have the case with a first, single unnamed field.
Only one such field can exist.
I'm not sure if that case exists in the ~25000 Qt5 functions, but in
that case, I think to give that single field the name "unnamed"
or maybe better "result".
Thank you very much for pointing me to that example!
Cheers -- Chris
On 08.08.19 06:41, Guido van Rossum wrote:
Alas, we didn't think of struct sequences when we designed PEP 484. It
seems they are a hybrid of Tuple and NamedTuple; both of these are
currently special-cased in mypy in ways that cannot easily be combined.
Do you really need anonymous fields?
I see an example in typeshed/stdlib/3/os/__init__.pyi (in
github.com/python/typeshed <http://github.com/python/typeshed>), for
stat_result. It defines names for all the fields, plus a __getitem__()
method that indicates that indexing returns an int. This doesn't help if
anonymous fields could have different types, not does it teach the type
checker about the number of anonymous fields.
--Guido
On Wed, Aug 7, 2019 at 1:51 AM Christian Tismer <tismer@stackless.com
<mailto:tismer@stackless.com>> wrote:
Hi all,
Ok, I am about to implement generation of such structures
automatically using the struct sequence concept.
One more question:
------------------
Struct sequences are not yet members of the typing types.
I would like to add that, because a major use case is also to
show nice .pyi files with all the functions and types.
* namedtuple has made the transition to NamedTuple
* What would I need to do that for StructSequence as well?
Things get also a bit more complicated since struct sequence
objects can contain unnamed fields.
Any advice would be appreciated, I am no typing expert (yet :-)
cheers -- Chris
On 30.07.19 17:10, Guido van Rossum wrote:
I think I have to agree with Petr. Define explicit type names.
On Tue, Jul 30, 2019 at 2:45 AM Paul Moore <p.f.moore@gmail.com
<mailto:p.f.moore@gmail.com>
<mailto:p.f.moore@gmail.com <mailto:p.f.moore@gmail.com>>> wrote:
On Tue, 30 Jul 2019 at 09:33, Christian Tismer
<tismer@stackless.com <mailto:tismer@stackless.com>
<mailto:tismer@stackless.com <mailto:tismer@stackless.com>>>
wrote:
> >>> typing.NamedTuple("__f", x=int, y=int)
> <class '__main__.__f'>
> >>> typing.NamedTuple("__f", x=int, y=int) is
typing.NamedTuple("__f",
> x=int, y=int)
> False
This appears to go right back to collections.namedtuple:
>>> from collections import namedtuple
>>> n1 = namedtuple('f', ['a', 'b', 'c'])
>>> n2 = namedtuple('f', ['a', 'b', 'c'])
>>> n1 is n2
False
I found that surprising, as I expected the named tuple type to be
cached based on the declared name 'f'. But it's been that way
forever
so obviously my intuition here is wrong. But maybe it would be
useful
for this case if there *was* a way to base named tuple
identity off
the name/fields? It could be as simple as caching the results:
>>> from functools import lru_cache
>>> cached_namedtuple = lru_cache(None)(namedtuple)
>>> n1 = cached_namedtuple('f', ('a', 'b', 'c')) # A tuple rather
than a list of field names, as lists aren't hashable
>>> n2 = cached_namedtuple('f', ('a', 'b', 'c'))
>>> n1 is n2
True
Paul
--
--Guido van Rossum (python.org/~guido <http://python.org/~guido>
<http://python.org/~guido>)
/Pronouns: he/him/his //(why is my pronoun here?)/
<http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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/Pronouns: he/him/his //(why is my pronoun here?)/
<http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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http://www.stackless.com/Karl-Liebknecht-Str. 121 :
https://github.com/PySide14482 Potsdam : GPG key -> 0xFB7BEE0E
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