Expose only Track() to users and internally decide between SingleTrack and PartialTrack?

[sehilyi]

I am wondering if it makes sense to expose gos.Track() only to users instead of the additional gos.PartialTrack(). I think whenever a user uses overlay alignment with tracks, we can internally consider this as PatialTrack so that users do not have to manually select between SingleTrack and PartialTrack.

bar_overview = bar_base.properties(
    width=300, height=300,
    alignment='overlay',
    tracks=[
        gos.Track(), // since overlay alignment is used with tracks, this is PartialTrack
        gos.Track().mark_brush().encode(x=gos.Channel(linkingId='detail-1')),
        gos.Track().mark_brush().encode(x=gos.Channel(linkingId='detail-2'))
    ]
)

[manzt]

I think this is a good idea, but unfortunately the types are distinct. Track currently inherits from gosling.schema.Track so it cannot be instantiated without arguments -- this is all autogenerated code that does validation. gos.Track just inherits some additional "mixins" that allow method chaining for assiging properties to the underlying gosling.schema.Track.

Another option would be to export a singleton of PartialTrack for use in this situation:

# gosling/api.py
track = PartialTrack()

# example.py
bar_overview = bar_base.properties(
    width=300, height=300,
    alignment='overlay',
    tracks=[
        gos.track, # since overlay alignment is used with tracks, this is PartialTrack
        gos.track.mark_brush().encode(x=gos.Channel(linkingId='detail-1')),
        gos.track.mark_brush().encode(x=gos.Channel(linkingId='detail-2'))
    ]
)

With that said, there is likely a way to make Track more "magical" and I'll take a look.

[manzt]

Another option would be to have a gos.track() util that inspects the arguments to decide whether to return a Track vs PartialTrack instance.

bar_overview = gos.track(data=data).properties(
    width=300, height=300,
    alignment='overlay',
    tracks=[
        gos.track(), # since overlay alignment is used with tracks, this is PartialTrack
        gos.track().mark_brush().encode(x=gos.Channel(linkingId='detail-1')),
        gos.track().mark_brush().encode(x=gos.Channel(linkingId='detail-2'))
    ]
)

The less magic the better IMO. And this is clearly a function that just adds some shorthand.

[sehilyi]

Closing this for now since I think this is addressed by #19 (comment)