Bind and panel Api: Make it easy to use widgets to select sub layouts

[MarcSkovMadsen]

Request

bind or panel like functionality to dynamically show value of widget, Parameterized or Parameter value.

Motivation

I'm trying to make a showcase for lightning.ai where a Select or RadioBoxGroup widget is used to select which sub component to show.

I would like to

• use the pn.bind api as that is the recommended one.
• not nest functions inside functions as that makes the logic hard to reason about and test.
• write simple and readable code

But I found it takes thinking and wrapper functions to support this very common workflow with the pn.bind api.

Code: As Is

import panel as pn

# I need a dict instead of list due to this regression: https://github.com/holoviz/panel/issues/3688
options = dict(
    PYTORCH=pn.Column("Start Training...", name="Pytorch"),
    KERAS=pn.Column("Not yet supported", name="Keras"),
)

selection = pn.widgets.RadioBoxGroup(options=options)

def to_value(value):
    # This is a wrapper function
    return value

sub_component = pn.bind(to_value, selection)

pn.Column(
    selection, sub_component
).servable()

Code: To be

If you define bind_to_value as

import panel as pn

def to_value(value):
    return value

def bind_to_value(widget):
    return pn.bind(to_value, widget)

the rest of the code becomes as simple and readable as

options = dict(
    PYTORCH=pn.Column("Start Training...", name="Pytorch"),
    KERAS=pn.Column("Not yet supported", name="Keras"),
)

selection = pn.widgets.RadioBoxGroup(options=options)

pn.Column(
    selection, bind_to_value(selection)
).servable()

Additional context

I've tried to consider the other apis. But I don't want to use interact or Parameterized classes here as pn.bind is the text book api to use. With watch you still need to create a wrapper function.

bind_to_value could also be called show_value which would make the code more readable. Or alternative pn.panel could work like bind_to_value for widgets and Parameters?