[IPython-dev] Link widget

[Jason Grout]

On 3/13/14, 12:59, Sylvain Corlay wrote:
> Quick question on the API:
>
> Does it really have to be a widget, or could it be a function in
> IPython.html.widgets.
>
> from IPython.html import widgets
> a = widgets.FloatSliderWidget(value=30)
> b = widgets.FloatSliderWidget()
>
> show(a)
> show(b)
>
> widgets.link([[a,'value'], [b,'value']])    # could be called "sync" as well
>

Somehow, the message has to get across to the javascript side that the 
models should be linked together.  We could send a message to, say, the 
widget manager to do that, but right now we don't have a good way to 
directly communicate with the widget manager and send it messages.  I 
hesitate to add such a messaging system when it seems even better to 
have the link object be a separate object we can manipulate by itself. 
By making the link a separate object (mirroring the link function in the 
traitlets file), it's easy to change the properties of the link, or 
abolish the link altogether.  That said, we could make a link() function 
in the widgets.py file that would construct, display, and return the 
Link object.

I chose the name link because that was what we decided to do in the 
traitlets case: https://github.com/ipython/ipython/pull/5060.

Thanks,

Jason