display_data and update_display_data in widget output not working as expected

I am trying to update the output after a slider callback (see attached GIF). Other displays change as expected, but the one below the slider does not update.

# In[1]:
ip = get_ipython()
import ipywidgets as widgets
def display_with_id(obj, display_id=None, update=False):
    iopub = ip.kernel.iopub_socket
    session = ip.kernel.session
    data, md = ip.display_formatter.format(obj)
    transient = {'display_id': display_id}
    content = {'data': data, 'metadata': md, 'transient': transient}
    if display_id is None: content.pop('transient')  # make display_id option
    msg_type = 'update_display_data' if update else 'display_data'
    session.send(iopub, msg_type, content, parent=ip.parent_header)
display = display_with_id
# In[2]:
display('initial display', 'some_destination')
# In[11]:
display('spoiler alert: output updated in both', 'some_destination')
# In[4]:
display('no output here, update above', 'some_destination', update=True)
# In[5]:
w = widgets.IntSlider()
# In[6]:
display(w)
# In[7]:
w.value = 13
# In[8]:
first_disp = True
# In[9]:
def value_change(change):
    global first_disp
    if first_disp:
        display('ABCDEFG', 'some_destination', update=False)
        first_disp = False
    else:
        display("Not first anymore!", "some_destination", update=True)
# In[10]:
w.observe(value_change, names='value')

[jasongrout]

Thanks. It does look like something is not quite right. We’ll check into it. A guess is that for some reason, the display region produced as a result of a widget action is not getting registered with the list of displays with that id.

FYI, you can also use an output widget for this sort of thing:

w = widgets.IntSlider()
out = widgets.Output()

display(w)
display(out)

def value_change(change):
    with out:
        print('new output')
w.observe(value_change, 'value')

See also https://ipywidgets.readthedocs.io/en/stable/examples/Widget List.html#Output

[wolfv]

thanks a lot for looking into this. I can currently work around it by creating a “widget-independent” display before creating the widget, but of course having the display connected to the widget would be nicer!

cheers!