Ignore None values in controls lists

[mnesarco]

Hi Friends,
In order to allow conditional controls in literal lists, Flet could ignore any None value, so we can write:

condition = ...
ft.Row([
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    ft.Text('Conditional Component') if condition else None, # <<---- This is not supported right now
    ft.IconButton(...),
]),   

I have implemented my own solution:

def control_list(*args):
    return [control for control in args if control is not None]

So we can do:

condition = ...
ft.Row(control_list(
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    ft.Text('Conditional Component') if condition else None, # <<---- Works
    ft.IconButton(...),
)),   

The previous code prevents the Component to be included depending on condition. But if I want the control to be included but initially invisible, there is also a solution:

def visible_if(control, predicate):
    control.visible = bool(predicate)
    return control

condition = ...
ft.Row(control_list(
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    ft.IconButton(...),
    visible_if(ft.Text('Conditional Component'), condition),
    ft.IconButton(...),
)),   

This kind if small utilities can help in code readability and expressing intention.