Type Promotion | Decoding Flutter

[@merthyr1831]

Good info, but also good to remember how messy this can make your code if you rely on it to 'simplify code'. Unless you're working with an annoying API you should always declare types as specific as possible because relying on type promotion is evidently dodgy

[@EdouardTavinor]

I'd say that a nullable type in dart or kotlin is like an option in scala or an optional in java. There's certainly a use-case for these types. This null check and type promotion is rather like a foreach in scala or Haskell.

[@francisgeorge7639]

tldr, dart can't predict the result through a getter as it could be overriden, so type promotion through a getter doesn't work without first setting to a local variable.

[@daviduribe4]

Not only overridden, their values could also change whenever they’re accessed!

[@francisgeorge7639]

@@daviduribe4 of course, forgot that though it did occur to me momentarily. Indeed that's the real reason.

[@rethinabair7344]

@@francisgeorge7639 guys correct me if I'm wrong but this code works fine class Animal { String get sound => 'Unknown sound'; } class Dog extends Animal { @override String get sound => 'Woof!'; } void main() { Animal animal = Dog(); if (animal is Dog) { print(animal.sound.toUpperCase()); } }

[@vivekkumar-nb3sw]

Thank you so much for Hindi subtitles.......it is really useful info for us...and i am expecting hindi subtitles for all the videos of this channel......thank you so much....love u guyz

[@flutterdev]

Thank you for the wonderful feedback, Vivek! We're glad to have you in the Flutter community 🙂

[@thomasmabika7291]

Excellent explanation! More intermediate to advance concepts please.

[@flutterdev]

We're delighted that you have enjoyed the video, Thomas. Keep an eye out for more videos coming your way!

[@LoneWolf-hg2ix]

"Nullable types are a union type of null and its underlying type..." Wouldn't that mean that technically union types already exist understood in dart? Probably in the nearest future we see it as a native language feature?

[@renotanumber]

FutureOr is also union type (may be older than non nullability?). Now imagine: FutureOr? is a union of: T, Future and null.

[@Raimkhodzhanov]

Thank You, it was very useful!

[@hussainkhuzema7083]

Truly awesome

[@youssef.elmoumen]

I like the way she's spelling shtring Great explanation 💞

[@farahrayis5928]

She's sweet

[@youssef.elmoumen]

@@farahrayis5928 Yes 🌸

[@cermilbonzo]

What color theme & font of your editor?

[@vatsaltanna5199]

Thanks for the video 🎉

[@RobFearn]

Nice explanation thank you!

[@flutterdev]

You're truly welcome, Rob. We're glad to have you a part of the Flutter community 👍

[@ajaykotiyal427]

sealed classes are now introduced in Dart 3.x

[@Tech1st]

Can i use var?

[@TungNguyen-lt5ej]

From Viet Nam with lov3!

[@aytunch]

PERFECT!

[@HuntingKingYT]

Heads up to Khanh Never gonna give you up! Nguyen

[@hideokuwaki]

This was great content!

[@flutterdev]

Thanks for the love, Hideo! We truly appreciate hearing what community members think about our content 🙌 If you enjoyed this, don't forget to check out more Decoding Flutter here: goo.gle/DecodingFlutter

[@bennguyen1313]

How does the variable-type followed by a question-mark work? for example when do you want to assign a null via "String?" "int?" vs "late var"?

[@andrewbrogdon558]

A type declaration like `int?` just means you're declaring a variable that can hold either an int value or null, in contrast to `int`, which *must* hold an int value at all times. The `late` keyword allows you to cheat a bit, essentially. If you declare a `late int`, you're telling the compiler three things: 1) You want a variable that must hold an int value, 2) you're not actually going to *give* it a value right away, but 3) you promise to stick a value in it before any code attempts to access that variable and use its value. So, you get some of the benefits of using a non-nullable variable (fewer null checks later in your code, for example), but you're also taking responsibility for making sure you assign a value to that variable before your app ever needs to read the value out.

[@normi6046]

Thanks!!

[@flutterdev]

Glad you enjoyed the video! Be sure to check out more episodes of Decoding Flutter here: goo.gle/DecodingFlutter Happy Fluttering 😎

[@kprakash9665]

Can we Build an Ecommerce Application by using Flutter Madam

[@nafeewalee]

Objection hearsay!

[@materialapp]

Compound, no foundation

[@rylaczero3740]

Well, gonna wait for sealed classes.

[@dharmasumansinghddharmasum8104]

Good infoso very good

[@flutterdev]

Happy to hear that the information provided was helpful! You can also check out the DartPad for this lesson here: goo.gle/3zcEobW Have a Fluttertastic day ahead 😁

[@mibi2007]

That's why I want to forget all of these check and go with functional programming for data and application layer in Flutter app :)

[@chouhanrahul]

😍

[@vinceramces]

type promotion should also infer type without needing to do nested if statement. For example, if(x != null) return x.copyWith(...)

[@philohan95]

Please give Dart an `if let` functionality like Swift.

[@fredgotpub871]

Pay attention, rickRoll towards the end.

[@dikatok]

objection your honor, rofl

[@fille.imgnry]

IT WAS NULL!! 😂

[@AiDidthis.]

😂 I thought there was a data type called Promotion

[@nicktech2152]

C# solves this in a more elegant way: if(maybeString is string stringForSure){ // do actions with stringForSure inlinly declared variable }

[@efliedus1267]

Literally 6 minutes on thing that must be avoided as much as possible in strict typed programming languages... But yeah for niche cases that knowledge is indeed useful

[@g0rbachov]

Straeng

[@joranmulderij]

28 views 9 likes? WOW!!