Dynamic number of widgets / params

Panel
2

OK I’m now doing this, I’m not sure if this is ‘correct’ but it works and I’m quite pleased with it. Turned out not to be that difficult.


class Colors(param.Parameterized):
    num = param.Number(3, bounds=(0, None))
    colors = param.List([])
    color_defaults = ['#1930e0', '#eded0e', '#cc0c49']
    
    def __init__(self, **param):
        super(Colors, self).__init__(**param)
        
        self.colors_col = pn.Column()
        for _ in range(self.num):
            self._add_color()
    
        self.param.watch(self.color_callback, ['colors'])
    
    
    def _add_color(self):
        try:
            default = self.color_defaults[len(self.colors_col)]
        except IndexError:
            default = '#FFFFFF'
            
        self.colors.append(default)
        widget = pn.widgets.ColorPicker(value=default)
        self.colors_col.append(widget)
        widget.param.watch(self.color_event, ['value'])
        
    def _remove_color(self):
        widget = self.colors_col.pop(-1)
        self.colors.pop(-1)
        [widget.param.unwatch(watcher) for watcher in widget.param._watchers]
        del widget
    
    @param.depends('num', watch=True)
    def _update_colors(self):
        while len(self.colors_col) != self.num:
            if len(self.colors_col) > self.num:
                self._remove_color()
            elif len(self.colors_col) < self.num:
                self._add_color()
        self.param.trigger('colors')

    def color_event(self, *events):
        for event in events:
            idx = list(self.colors_col).index(event.obj)
            self.colors[idx] = event.new
        self.param.trigger('colors')
        print(self.colors)
                
    def panel(self):
        return pn.Column(pn.Param(self.param), self.colors_col)
                 
        
    def color_callback(self, events):     
        print(events)
                    
c = Colors()
c.panel().servable()

I’ve tried to obliviate the widget that gets removed but not very successfully, if i make a weakref to the widget that still persists.

EDIT: Added a color list that holds the colors. I trigger it manually because assigning elements doenst trigger it. It works well but the field showing the value of the list doesnt uptake (although I dont need this atm)

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