C#•3y ago

❔ Nullable bools

I just got into the situation where I needed to use nullable bools and I'm a little confused about how the compiler handles things. If I write my code like shown in picture 1 the compiler still thinks the variable

accessScopesSupported

accessScopesSupported

might be null inside the codeblock with an explicit check for null. If I use

.Value

.Value

inside the codeblock the compiler understands that the value cannot be null. My question is why? Shouldn't the null check be enough?

RobinTTYOP•5/24/23, 5:14 PM

Here maybe a better screenshot, I wouldn't have expected the "possible null reference" here.

RobinTTYOP•5/24/23, 5:16 PM

NullReference•5/24/23, 5:25 PM

by itself, the bool variable cannot accept null, but since it is there? the variable can accept null

RobinTTYOP•5/24/23, 5:25 PM

Ok should have thought longer. ToString always returns a

string?

string?

ero•5/24/23, 5:26 PM

why does the bool need to be nullable?

RRobinTTY Ok should have thought longer. ToString always returns a `string?`.

NullReference•5/24/23, 5:26 PM

if variable was null, ToString return null

ero•5/24/23, 5:26 PM

that is incorrect

Eero why does the bool need to be nullable?

RobinTTYOP•5/24/23, 5:27 PM

it is a case where if something isn't sent to an API it will return a different result from when a "false" or "true" is sent. All 3 have different outcomes

ero•5/24/23, 5:27 PM

sure, question remains

RobinTTYOP•5/24/23, 5:27 PM

what question?

Eero why does the bool need to be nullable?

ero•5/24/23, 5:27 PM

Eero that is incorrect

NullReference•5/24/23, 5:27 PM

MODiX•5/24/23, 5:28 PM

Ero#1111

REPL Result: Success

int? i = null;
i.ToString()

int? i = null;
i.ToString()

Result: string

Compile: 531.812ms | Execution: 28.921ms | React with ❌ to remove this embed.

RobinTTYOP•5/24/23, 5:28 PM

I don't understand the question in that case

MMODiX Empty message

ero•5/24/23, 5:28 PM

this is news to me

Eero this is news to me

NullReference•5/24/23, 5:28 PM

for me too

MODiX•5/24/23, 5:28 PM

Ero#1111

REPL Result: Failure

List<string>? foo = null;
foo.ToString()

List<string>? foo = null;
foo.ToString()

Exception: NullReferenceException

- Object reference not set to an instance of an object.

- Object reference not set to an instance of an object.

Compile: 497.655ms | Execution: 35.858ms | React with ❌ to remove this embed.

ero•5/24/23, 5:29 PM

yeah, that

RRobinTTY I don't understand the question in that case

ero•5/24/23, 5:29 PM

have a method overload that does not take a bool

Eero yeah, that

NullReference•5/24/23, 5:29 PM

how do you do that?

ero•5/24/23, 5:29 PM

async Task MyApiCaller() { }
async Task MyApiCaller(bool b) { }

async Task MyApiCaller() { }
async Task MyApiCaller(bool b) { }

NNullReference how do you do that?

ero•5/24/23, 5:29 PM

!e

!e

RobinTTYOP•5/24/23, 5:31 PM

It seems natural to me, if you don't want something to be in the query string to the API you specify it as null. If you want it to be there you either choose true or false. But this is of course arguable

RobinTTYOP•5/24/23, 5:31 PM

and my default is just null so calling the method is not any harder

ero•5/24/23, 5:32 PM

what lol

ero•5/24/23, 5:32 PM

if you don't want something in a query, you don't specify it at all

ero•5/24/23, 5:32 PM

not specify it as null

ero•5/24/23, 5:32 PM

null is distinctly different from nothing

RobinTTYOP•5/24/23, 5:32 PM

yes right that's why the default is null

ero•5/24/23, 5:33 PM

what a cumbersome way to do this

RobinTTYOP•5/24/23, 5:33 PM

it has the same outcome as the overload

RobinTTYOP•5/24/23, 5:33 PM

lol

ero•5/24/23, 5:33 PM

shrug, i think it's ugly to work with nullable value types

RobinTTYOP•5/24/23, 5:34 PM

Sure that's taste

NullReference•5/24/23, 5:35 PM

I like what we're talking about and our avatars
But a variable of type bool with a null value is strange.

RobinTTYOP•5/24/23, 5:36 PM

Haha, yeah first time I needed to use it as well. But it seemed very much made for this kind of problem to me. But maybe I'm completely off on this one

RobinTTYOP•5/24/23, 5:38 PM

It was already weird to me that the API accepts a boolean query string but returns different data for 3 cases (query string not sent, true sent, false sent)

RRobinTTY Haha, yeah first time I needed to use it as well. But it seemed very much made f...

NullReference•5/24/23, 5:38 PM

no one understands programming well enough. God is rated 5, everyone else is rated 3

NullReference•5/24/23, 5:39 PM

RRobinTTY Click to see attachment