在TornadoFX中，如何更改其他属性？

Question

For example, I want to do this: I have a StringProperty, and it is a combination of an IntegerProperty and anoter StringProperty, like this:

• StringProperty A = "foo"
• IntegerProperty B = 3
• resulting StringProperty C = "foo 3"

How can I "bind" properties so that the C changes when either A or B are changed? (Note that I don't want to react to changes made to C)

I tried using stringBinding() method, but it is unclear to me how this method works exactly, and the documentation about it is unclear.

Answer 1

stringBinding is what you want. The first argument will become this inside the calculation block, and if this is an observable value, it will be added as a dependency used to calculate when the string binding should be reevaluated. The rest of the parameters (only b here) are added as re-evaluation dependencies as well.

If you do stringBinding(a, b) { "${a.value} ${b.value}" } , you have created a string binding that will update whenever either a or b changes. Since this is a in the above example, you could also have written in stringBinding(a, b) { "${this.value} ${b.value}" } but I don't think that makes it any clearer :)

The reason we decided to make the first element this is made more apparent by the following example:

val sizeDescription = bind(items) { "$size elements in list" }

Here you don't need to reference the items again to get to it's size property.