I’m trying to implement configurable key bindings in tt. Boy, is parsing the key names into tcell.EventKeys a horrible thing. This type consists of three information:

1. maybe a predefined compound key sequence, like Ctrl+A
   
2. maybe some modifiers, such as Shift, Ctrl, etc.
   
3. maybe a rune if neither modifiers are present nor a predefined compound key exists
   

It’s hardcoded usage results in code like this:

func (t *TreeView[T]) InputHandler() func(event *tcell.EventKey, setFocus func(p tview.Primitive)) {
    return t.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p tview.Primitive)) {
        switch event.Key() {
        case tcell.KeyUp:
            t.moveUp()
        case tcell.KeyDown:
            t.moveDown()
        case tcell.KeyHome:
            t.moveTop()
        case tcell.KeyEnd:
            t.moveBottom()
        case tcell.KeyCtrlE:
            t.moveScrollOffsetDown()
        case tcell.KeyCtrlY:
            t.moveScrollOffsetUp()
        case tcell.KeyTab, tcell.KeyBacktab:
            if t.finished != nil {
                t.finished(event.Key())
            }
        case tcell.KeyRune:
            if event.Modifiers() == tcell.ModNone {
                switch event.Rune() {
                case 'k':
                    t.moveUp()
                case 'j':
                    t.moveDown()
                case 'g':
                    t.moveTop()
                case 'G':
                    t.moveBottom()
                }
            }
        }
    })
}

This data structure is just awful to handle and especially initialize in my opinion. Some compound tcell.Keys are mapped to human-readable names in tcell.KeyNames. However, these names always use - to join modifiers, e.g. resulting in Ctrl-A, whereas tcell.EventKey.Name() produces +-delimited strings, e.g. Ctrl+A. Gnaarf, why this asymmetry!? O_o

I just checked k9s and they’re extending tcell.KeyNames with their own tcell.Key definitions like crazy: https://github.com/derailed/k9s/blob/master/internal/ui/key.go Then, they convert an original tcell.EventKey to tcell.Key: https://github.com/derailed/k9s/blob/b53f3091ca2d9ab963913b0d5e59376aea3f3e51/internal/ui/app.go#L287 This must be used when actually handling keyboard input: https://github.com/derailed/k9s/blob/e55083ba271eed6fc4014674890f70c5ed6c70e0/internal/ui/tree.go#L101

This seems to be much nicer to use. However, I fear this will break eventually. And it’s more fragile in general, because it’s rather easy to forget the conversion or one can get confused whether a certain key at hand is now an original tcell.Key coming from the library or an “extended” one.

I will see if I can find some other programs that provide configurable tcell key bindings.