Is this Unresolved reference 'insert' on the String struct because of SKIP?

[davidakoontz]

I'm pulling my hair out - trying to understand why the Compile is giving me all these:
Unresolved reference 'insert'. Errors when trying to use the simple plan old String.insert() function.

Is it because SKIP does NOT support this API call yet?

Looking at the Skip-Lib String - I do NOT see 'insert' but do I interpret that as NOT Supported? Unsure!

[marcprux]

As you point out in the reference to https://skip.tools/docs/modules/skip-lib/#swift-standard-library-support, Kotlin strings are not mutable, and so we cannot support functions like insert. The workaround is to do something like:

greet = atSign + greet

[davidakoontz]

Hey Marc, @marcprux , as I've pondered this issue a while now, it is not making sense to me.

Swift Strings are also non-mutable and yet the Swift Lib allows many functions that mutate the original String. I believe the Kotlin library does a very similar trick. They return a new string upon "write". This would be very similar to how the capitalized computed property works. And how the function trimmingCharacters(in set: CharacterSet) -> String works.

So since I've got an App that is going to need a few String mutating functions... I guess I have to write them myself. OK... is there a way I could contribute this code to the SKIP project... if it was of high quality/robustness?

Do you have ANY suggestion for how to start ....

[marcprux]

Functions like trimmingCharacters(in set: CharacterSet) -> String return a new String, rather than mutating the existing string. We also do that in Skip. For example, String.lowercased() works fine, because it is returning a new String. It is the mutating functions on built-in types that we are unable to support. For example, we can't support booleanField.toggle() for this reason – the workaround is similar: do booleanField = !booleanField instead.

[davidakoontz]

Ahhh, thank you @marcprux; now I'm starting to get the lay of the land... it's Swift's mutating func that is not supported / compatible with Kotlin. OK I'm slow but starting to catch the drift. I know next to nothing about Kotlin world.

So the acceptable solution with Swift mutating func pattern is ... what?

var phrase = "Backya!"
let position = 4
#if !SKIP 
    phrase.insert("@", at: position)   // "Back@ya!"
#else
     // kotlin - workaround for string.insert
     // written in Swift code - but transpired to Kotlin
     let wordOneEndPosition = phrase.firstIndex(of: "y")!
     let wordOne = phrase[...wordOneEndPosition]
     let sentence = wordOne + "@" + "ya!"
     // now do something with sentence
     let phrase = sentence
#end if
    

Is this correct thinking?

[davidakoontz]

Still seeking understanding @marcprux,

Docs said: "The following table summarizes SkipLib’s Swift Standard Library API support on Android. Anything not listed here is likely not supported. Note that in your iOS-only code - i.e. code within #if !SKIP blocks - you can use any API you want."

I see that in Skip-Lib the Collection contains:
mutating func insert( newElement: Element, at i: Int)_

And does String implement Collection as a protocol? Or maybe NOT???

Should I be looking to cast my String to a Collection? So that I can use the insert method?