Cascading widgets (Re: Improved url-quote-magic)

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

[redirected from -users to -workers]

On Oct 27, 12:36pm, Peter Stephenson wrote:
}
} Bart Schaefer wrote:
} > To repeat my comment from 5424:  Hey, zsh-workers, there's no good way
} > to "stack" functions like this one so that, e.g., you could use it at
} > the same time as insert-and-predict.
} 
} I don't quite know what that means, but it seems to be something like
} having a stream of data from the keyboard which gets modified and then
} passed up to some other handler as if it came raw.

No, that's not what I had in mind.  For one thing, the data from the
keyboard is less interesting than the state of the buffer after the
widget has executed.

In the case of predict-on/predict-off, executing predict-on redefines
self-insert and executing predict-off sets it back to ".self-insert".
If self-insert had previously been redefined as url-quote-magic, that
binding is lost.  Widget push/pop can be fudged with "zle -A" as you
did in minibuffer-{push,pop}-widget, but only at the risk of name
collisions.  Maybe that's minimal enough that we shouldn't worry.

More generally, though, I might prefer to have url-quote-magic quote
the input key and then still have insert-and-predict attempt to find
a matching line.  For this to work right now, predict-on would have
to remember the previous self-insert binding, and insert-and-predict
would have to call that widget rather than modifying LBUFFER directly.
That breaks down as soon as there are two such widgets; they'll end up
infinitely calling back to one another.

I guess I'm just looking for a way to generalize such cascades, so
that widget writers don't have to think explicitly about it.  Maybe
something similar to "compset" but that could be called to change
the ZLE state, which would keep track of the "stack position" and do
the calls to the previous incarnations of various widgets.  I admit I
haven't thought this through very far yet; it would need options to
specify insertions, deletion ranges, modification ranges, etc.