Introduce the instruction concept

[toth-istvan-zoltan]

Modifying the appearance of elements is done different ways on different platforms:

• CSS in browsers, many different libraries and approaches
• constraints / class attributes on Android and in Swift (I think)
• Modifiers in Compose

The instruction concept is an abstraction inspired by Tailwind and Compose modifiers.

fun main() {
    browser {
        hello(padding_10, border_1, border_color_black, /* the other parameters */)
    }
}

@Adaptive
fun hello(vararg instructions : AdaptiveInstruction, /* other parameters */) {
    /* whatever hello does */
}

The actual implementation of the instruction should be adapter dependent:

val padding_10 = AdaptiveInstruction("padding_10")

object CssInstructionFactory : Registry<AdaptiveInstruction> {
    init {
        + CssAdaptiveInstruction(padding_10, "padding: 10px"))
    }
}

AndroidAdaptiveInstruction({ it.setPadding(10) })

object AndroidInstructionFactory : Registry<AdaptiveInstruction> {
    init {
        + AndroidAdaptiveInstruction(padding_10) { it.setPadding(10) }
    }
}

Cons:

• code size
• runtime CPU cost

Pros:

• general approach, works for each platform
• easy to read
• easy to extend
• matches well with adaptive state (if the instruction set changes the UI should change as well)
• easy to offer the user alter / patch functionality
• makes the fragment tree searchable by instruction

[toth-istvan-zoltan]

Implemented the basic concept.