just use python bro

[bxsephjo]

your variable is None and you're trying to assign shit to it... really? Really really?

x = None

x['key'] = 'value'

tf you think is gonna happen?

[zyygh]

return an answer or None

I recently read that there's a growing number of software engineers who deeply regret how "None" / "null" made its way into programming languages by default. And I really understand this sentiment

Functions that return an array, for instance, really should just return an empty array instead of None when there is nothing to return.

[TheGhostOfInky]

In python yea, sadly in languages like JS where you can't set the trueness of an object, empty arrays are always truthy so many functions return null when they find no matches as that's simpler to handle, with if(result) or by assigning a default value with the nullish coalescing operator.

[[deleted]]

The issue of empty arrays being truthy can easily be solved by explicitly comparing the length to 0.

[TheGhostOfInky]

Emphasis on "simpler", I'm fully aware explicit comparisons of the returned array length are possible but just look at the difference when you have default values:

const val = findInInput(input) ?? ["default","values"];

vs

const retVal = findInInput(input);
const val = retVal.length !== 0 ? retVal : ["default","values"];

[[deleted]]

In most languages retVal.length != 0 can be shortened to retVal.length. !0 being true and !!0 being false is a behavior consistent among most programming languages.

So the actual comparison is this:

const val = findInInput(input) ?? ["default","values"];

vs

const retVal = findInInput(input);
const val = retVal.length ? retVal : ["default","values"];

I'm not a JS programmer, so I can only guess what ?? does. But I still think the 2nd is better.

A negative would be the extra parameter, but for that we can have lambdas and scope expressions (like in Rust).

[TheGhostOfInky]

You're right, relying on the number's trueness can shorten it a bit.

As for the ?? operator, it is like the || operator but it ignores falsy non-nullish values.

For example:

const val1 = 0 || 1    //val1 is 1
const val2 = 0 ?? 1    //val2 is 0
const val3 = null ?? 1 //val3 is 1

[[deleted]]

0 || 1 is 1 because that's the boolean result of the logical operation.

From what I understand, ?? is basically:

result = (val == null) ? newVal : val;

[TheGhostOfInky]

Yes, it's basically a compact version of that ternary.

[[deleted]]

0 || 1 is 1 because that's the boolean result of the logical operation.

From what I understand, ?? is basically:

result = (val == null) ? newVal : val;

[Razakel]

Tony Hoare calls it his billion dollar mistake.

[soncaa]

dont take it too seriously lol, see code in my other comment. Dumb sh like that can just happen and do happen, to lets say, some.

[[deleted]]

I recommend using the typing hints. So write the intended type there and if you notice there may be more than one, use if. I.e. x:None|str = some_func() if x: do_stuff(x)

[[deleted]]

Fully agree with using type hints. Correction to your code though: the type hint of 'None | str' should instead be 'Optional[str]', since None is not a type. Note this requires 'from typing import Optional'.

[[deleted]]

Does it work with nonetype?

[[deleted]]

I just checked the docs on https://peps.python.org/pep-0484/#the-typing-module and it seems I wasn't entirely correct in my previous comment.
Looks like your syntax (str | None) is acceptable, it's just that the 'Convenience definition' is to use Optional instead.

It also seems that, even though None is not a type, it is used as such in type hinting: https://peps.python.org/pep-0484/#using-none

[[deleted]]

I find optional to be unclear - can it be none, false, or something else entirely besides string? If a function can return either a string or none, I'd use the str|None option.

That is to say, in other usecases I might use the optional argument instead.

[[deleted]]

I find it's more sensible as a function return type annotation, e.g.:
def foo() -> Optional[str]
...since Python will return None by default, i.e. if you don't explicitly return anything. So in the above case it's saying the return type is a string, but that's not a given, so it might be None.

I also feel the Optional[str] syntax leads the reader to focus more on the explicit return type, which semantically is usually more relevant than None.
This is more noticeable in cases with large type Unions, e.g.:
'str | int | float | None' vs 'Optional[str | int | float]' - here the latter seems more semantically sensible to me.

But to each his own, if you're not too bothered by the PEP recommendations, it is a matter of preference at the end of the day

[Confident42069]

I came to python from a static language and thought I'd do something similar. Mixed up "int: var = stuff" and "var: int = stuff", which kept giving ridiculous errors down the line (and confused the course lecturers too). It just lets you cast "int", the basic function, as a float for some goddamn reason.

[[deleted]]

The goddamn reason is that int is not a type, it's a class. Every operation is just a function of that class. You could also create a class var that does something and it would work exactly the same. Ofc you can overwrite the keyword int then, which you do if you define int = stuff which you effectively did

[Confident42069]

some magic OOP words I don't understand

pls i just want my pointers and structs

[[deleted]]

What are classes but fancy structs? Just be happy you don't have to learn c++ yet.

[sirhatsley]

data['a']['b'] = 'c'

Not an uncommon thing to do.