Support reading other properties than value? about ipython_blocking

[kafonek]

@bryceschober for any kind of situation where you're working with non-standard widgets or have some complex validation (like multiple widgets being filled out), the best thing to do with ipython_blocking is define a function to block on. Basically at every step (kernel.do_one_iteration()) it will run your blocking function. If the function returns True, it breaks out of the blocking context. If not, it stays in the blocking context.

For FileChooser, try this out:

### cell 1
import ipyfilechooser
fc = ipyfilechooser.FileChooser()

def block_until_selected():
    return bool(fc.selected)

fc

### cell 2
import ipython_blocking

%block block_until_selected

### cell 3
### will not run until a file is selected in cell 1
fc.selected

[bryceschober]

Yep, that ended up being simpler, thanks.

[bryceschober]

@kafonek After I requested it, ipyfilechooser now inherits from ValueWidget and implements get_interact_value(), but that seems to not be enough for ipython_blocking...