inline class PropertyOrValue<T>

[Miha-x64]

A zero-cost wrapper which acts like Property<T> | T.

// pseudokode, won't kompile
inline class PropertyOrValue<T> {
    private val _value: Any? // = Property<T> | T
    constructor(value: T) {
        this._value = // guard against the (rare) case when value is also a property:
            if (value is Property<*>) immutablePropertyOf(value)
            else value
    }
    constructor(property: Property<T>) {
        this._value = property
    }
    val value: T
        get() = (if (_value is Property<*>) _value.value else _value) as T
    // TODO: addChangeListener(On), removeChangeListener
}

Use-cases:

• universal [library] components which accept some Properties may accept PropertyOfValue instead, allowing caller to avoid wrapping value into ImmutableProperty
• Android resources: (typedValue.changingConfigurations & activityInfo.configChanges) == 0 implies Value, else Property (not sure how popular this case is, taking into account that resources are good at storing strings, but other resource types — animations and animators, drawables, colours and colour state lists, layouts, menus, styles, fonts, scalars and scalar arrays — are mostly useless)