Python 3.10 introduces the | union operator into type hinting, see PEP 604. Instead of Union[str, int] you can write str | int. In line with other type-hinted languages, the preferred (and more concise) way to denote an optional argument in Python 3.10 and up, is now Type | None, e.g. str | None or list | None.

A Python function can take in some arguments, take this for example, def add(x,y): return x+ y # calling this will require only x and y add(2,3) # 5 If we want to add as many arguments as we may want, we shall just use *args which shall be a list of more arguments than the number of formal arguments that you previously defined ( x and y ).

Oct 4, 2021 · Now that Python 3.10 has been released, is there any preference when indicating that a parameter or returned value might be optional, i.e., can be None. So what is preferred: So what is preferred: Option 1:

Jun 30, 2024 · Since your return type can either be datetime (as returned from datetime.utcnow()) or None you should use Optional[datetime]: from typing import Optional def get_some_date(some_argument: int=None) -> Optional[datetime]: # as defined From the documentation on typing, Optional is shorthand for: Optional[X] is equivalent to Union[X, None].

May 27, 2015 · It's a good idea, but there's an issue: argparse allows partial matches for optional arguments if there is no ambiguity. (For example if you have a flag --option then --opt will work if there is no other flag that starts with "opt" .)

Jan 22, 2022 · By Optional I mean __dict__ may contain the key "missing_flask_size" or not. If I set a default value then the key will be there and it shouldn't be in some cases. If I set a default value then the key will be there and it shouldn't be in some cases.

Sep 15, 2015 · $ python myfile.py -v version flag given $ python myfile.py --version version flag given $ python myfile.py version flag not given Optional arguments (e.g. --installdir /usr/bin/) One could argue that, in your case, you would be better off with an optional argument rather than a positional one. myfile.py

Jul 6, 2012 · Also, in case you need both default values and optional mutability, Python 3.7 is going to have data classes (PEP 557) that can in some (many?) cases replace namedtuples. Sidenote: one quirk of the current specification of annotations (expressions after : for parameters and variables and after -> for functions) in Python is that they are ...

I would like to make these invocations of myprog work, and no others. $ python3 myprog.py -i infile -o outfile $ python3 myprog.py -o outfile $ python3 myprog.py -o $ python3 myprog.py In particu...

Aug 6, 2013 · python dataclasses with optional attributes Hot Network Questions Apparent inconsistencies between <sObject>.sObjectType.getDescribe() and Schema.sObjectType.<sObject>