C#•3mo ago

assure compiler type is not null

i have a code that early returns if a property is null. how do i tell the compiler the property is not null afterwards?

20 Replies

Angius•3mo ago

if (FilePath is not {} path)
{
    return;
}
// `path` is not null

if (FilePath is not {} path)
{
    return;
}
// `path` is not null

cheeze2000•3mo ago

what is this called? and where can i learn about this

Angius•3mo ago

Just a part of pattern matching

reflectronic•3mo ago

this tells it that it is not null there is nothing more you need to do

maxmahem•3mo ago

variables declared as var's always shows up as nullable in inspection. That doesn't mean the compiler sees it as nullable, if that makes sense?

reflectronic•3mo ago

whether the variable is declared as nullable is different from whether it is null right now

reflectronic•3mo ago

are you on an updated version of the C# extension? it should tell you this

cheeze2000•3mo ago

this is mine

cheeze2000•3mo ago

reflectronic•3mo ago

well, yes... if it's not null, you return so, if you didn't return, it's null

cheeze2000•3mo ago

wait... what am i doing

reflectronic•3mo ago

if you change it to is null that the warning will go away

cheeze2000•3mo ago

ok i have another one public Range? Location { get; init; }

cheeze2000•3mo ago

reflectronic•3mo ago

yes, that's because Range is a struct

cheeze2000•3mo ago

ohhh

reflectronic•3mo ago

(probably) it means that Range? is a Nullable<Range> which means, you need to unrap the value manually you can do it using range.HasValue, with range.Value or range.GetValueOrDefault() you can also use the pattern matching if (Location is not Range r) or if (Location is not { } r)

cheeze2000•3mo ago

thanks! can i use this pattern matching on the FilePath too? if (FilePath is not string path)

reflectronic•3mo ago

yes

cheeze2000•3mo ago

FilePath is string? ok nice

Gaming

Programming

assure compiler type is not null