I’d like a convenience extension to return true when a nullable string is not null, and not blank — neither should be processed. After the extension returns true for an immutable, I don’t want to have to have to

!!

it. But it seems I can’t use “this” in a contract:

contract {
        returns(true) implies (this != null)
    }

    return !this.isNullOrBlank()

Is there a way to do this?

you need to use a qualified this instead, and so assuming your function is called

myCastAsNullOrBlankFun

, then your contract should be this:

contract {
    returns(true) implies (this@myCastASNullOrBlankFun != null)
}

Why you use a contrat ?

fun String.isNullOrBlank()

itself has a contract,

contract {
    returns(false) implies (this@isNullOrBlank != null)
}

@Youssef Shoaib [MOD] perfect, thanks!