Hi is it possible to have a default value for a generic type of a class Like that code in TypeScript ```class Test lt T = string gt readonly thing T const a = new Test this works const b = new Test lt number gt this too```

If you are saying `T` can be a subclass of `String` you could do ```class Test lt T String gt ```

Could you not do fun Test = Test lt String gt

Typealiases can do this ```class Test lt T gt typealias DefaultTest = Test lt String gt ``` Not an ideal solution but the closest you can get until we have native support for this in the language

Hi is it possible to have a default value for a generic type kotlinlang #getting-started

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Ayfri

08/08/2021, 2:42 AM

Hi, is it possible to have a default value for a generic type of a class ? Like that code in TypeScript :

class Test<T = string> {
    readonly thing: T
}

const a = new Test() // this works
const b = new Test<number>() // this too

Nathan Bedell

08/08/2021, 2:59 AM

Hi, unfortunately it looks like this hasn't been implemented yet. I'd love to see something like this feature though!

😕 1

James Whitehead

08/08/2021, 4:31 AM

If you are saying

can be a subclass of

String

you could do

class Test<T : String> {}

Dave K

08/08/2021, 4:47 AM

It looks like they’re wanting to omit the <> entirely and have the default implication be that it’s a string, but also support other things explicitly such as Number

Could you not do fun Test() = Test<String>()

:blob-open-mouth: 1

with constructor arg or not https://pl.kotl.in/mJLv3yyUg Though with the lateinit var has to have a non nullable value and also isn’t read only. However since the example didn’t have a constructor argument I wasn’t sure what the intended use was

If you’re using a constructor argument then the type may not even be necessary to specify explicitly https://pl.kotl.in/pfl7VDG97

Ayfri

08/08/2021, 2:21 PM

This is nice thanks ! Also is there a workaround for interfaces (with also a generic type an some properties that have that type) ?

diesieben07

08/08/2021, 2:29 PM

Typealiases can do this:

class Test<T> { }
typealias DefaultTest = Test<String>

Not an ideal solution but the closest you can get until we have native support for this in the language.

👍 1

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