No @Gerard, YOU weren't missing anything: since posting, have upgraded
PyCharm to 2022.3.2 and the complaints about 'Method 5' have
disappeared. Evidently a PyCharm issue!
Which alters the top-line question to: is numbers.Number the preferred
type-hint when multiple numeric types are to be accepted?
PS no Decimal(s) nor Fraction(s) in my situation, but may be worth
adding to a wider discussion...
On 06/02/2023 04.03, Weatherby,Gerard wrote:
dn,
I’m missing something here. Method 5 seems to work fine in PyCharm. I’m
interpreting your statement as:
from fractions import Fraction
from numbers import Number
def double(value: Number):
if isinstance(value, Number):
/# noinspection PyTypeChecker
/return 2 * value
raise ValueError(f"{value}of {type(value)}is not a Number")
print(double(7))
print(double(7.2))
print(double(complex(3.2, 4.5)))
print(double(Fraction(7, 8)))
/# print(double("7")) PyCharm properly complains/
*From: *Python-list <python-list-bounces+gweatherby=uchc....@python.org>
on behalf of dn via Python-list <python-list@python.org>
*Date: *Saturday, February 4, 2023 at 9:32 PM
*To: *'Python' <python-list@python.org>
*Subject: *Typing Number, PyCharm
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Do we have a typing type-hint for numbers yet?
Often wanting to combine int and float, discovered that an application
was doing a walk-through with/for uses three numeric types. Was
intrigued to note variance, in that the code-set features two different
methods for typing, in this situation:
def func( value ):
...using value...
where value may be an integer, a floating-point value, or a
complex-number (but not decimal-type).
NB code snippets from memory (cf copy-paste)
Method 1 (possibly older code):-
from typing import Union
...
def fun( value:Union[ int, float, complex ] ):
Method 2:-
def fun( value:int|float|complex ):
Pondering this, realised could use an alias to de-clutter the
function-definition/signature:
Method 3:-
number_type = int|float|complex
...
def fun( value:number_type ):
If it was important to have type consistency within the union, eg
argument and return, could go for:
Method 4:-
from typing import TypeVar
number_type = TypeVar( 'number_type', int, float, complex )
...
def fun( value:number_type ):
Then remembered the way we'd code an execution-time check for this using
isinstance():
Method 5:-
from numbers import Number
...
def fun( value:Number ):
Each of these will execute correctly.
All cause PyCharm to object if I try to call the fun(ction) with a
string parameter - and execute an exception, as expected.
Accepting all the others, am curious as to why PyCharm objects to Method
5 with "Expected type 'SupportsFloat | SupportsComplex | complex |
SupportsIndex', got 'Number' instead? - yet still highlights the
erroneous string parameter but none of the 'legal' data-types?
As soon as a list (in this case types) reaches three, my aged-eyes start
to think de-cluttering is a good idea!
Do you know of another way to attack this/more properly?
--
Regards,
=dn
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