feat: Implement stream.from_param

[ahuang11]

Closes #6384

Wondering how to bidirectionally link it.

Currently, the widgets can update the point location, but tapping does not update the widgets

Screen.Recording.2024-09-27.at.2.36.22.PM.mov

import param
import holoviews as hv
import panel as pn

pn.extension()

class TapTest(pn.custom.PyComponent):

    x = param.Number(default=1, allow_refs=True)
    y = param.Number(default=0.5, allow_refs=True)

    def __init__(self, **params):
        super().__init__(**params)

        self._tap = hv.streams.Tap.from_param(x=self.param.x, y=self.param.y)
        hv_pane = pn.pane.HoloViews(object=hv.DynamicMap(self.plot, streams=[self._tap]))
        self._layout = pn.Column(hv_pane, self.param.x, self.param.y)

    def plot(self, x, y):
        return hv.Points([(x, y)]).opts(tools=['tap'], xlim=(0, 2), ylim=(0, 2))

    def __panel__(self):
        return self._layout

tap_test = TapTest()
tap_test.show()

[codecov]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.49%. Comparing base (017361b) to head (7a75695).
Report is 47 commits behind head on main.

Files with missing lines	Patch %	Lines
holoviews/streams.py	92.85%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #6396    +/-   ##
========================================
  Coverage   88.48%   88.49%            
========================================
  Files         323      323            
  Lines       68459    68673   +214     
========================================
+ Hits        60579    60769   +190     
- Misses       7880     7904    +24     

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[ahuang11]

@philippjfr

TapStream works bidirectionally, however, Range* streams seem to only work with adjusting the zoom on the plot, and not manually adjusting the widget, i.e. when I change the widget value, the plot's xlim doesn't update.

import param
import holoviews as hv
import panel as pn

pn.extension()

class StreamTest(pn.custom.PyComponent):

    x_range = param.Range(default=(0, 10))

    def __init__(self, **params):
        super().__init__(**params)

        self._rangexy = hv.streams.RangeX.from_param(x_range=(self.param.x_range))
        hv_pane = pn.pane.HoloViews(object=hv.DynamicMap(self.plot, streams=[self._rangexy]).apply.opts(xlim=self.param.x_range))
        self._layout = pn.Column(hv_pane, self.param.x_range)

    def plot(self, x_range):
        return hv.Points([0, 0])

    def __panel__(self):
        return self._layout

tap_test = StreamTest()
tap_test.show()

[holovizbot]

This pull request has been mentioned on HoloViz Discourse. There might be relevant details there:

https://discourse.holoviz.org/t/whats-the-best-practice-for-linking-up-holoviews-streams-with-parameterized/8215/7