Mature intermediate tutorials

[MarcSkovMadsen]

No description provided.

[MarcSkovMadsen]

This application does not seem very robust. As soon as I drag one of the range slider the chart does not show anything.

And moving the range slider back in place does not display anything in the plot again.

[philippjfr]

Will follow up in a new PR.

[Coderambling]

Maybe add a a small hint what rx(something01)(something02) does? I have not seen the () () notation with .rx before (but maybe it's obvious to most people?)

[MarcSkovMadsen]

pn.rx(some_func)(something1, something2) can be used as pn.bind(some_func, something1, something2) and is the same as pn.bind(some_func, something1, something2).rx().

Its introduced and used in the basic tutorial https://holoviz-dev.github.io/panel/tutorials/basic/pn_rx.html. That is why I don't explain it here.

[Coderambling]

Or rather pn.rx is the successor of pn.bind`.? This is good to know by the way, I did not realize this before. Is there a separate section somewhere regarding this in the docs (starting with the pn.bind) documentation?

Something that says at the top: We recommend pn.rx instead of pn.bind from now on? And a link to a migration tutorial that covers most cases of how best to change existing code that uses pn.bind?

[MarcSkovMadsen]

I think I will have to update that. We discussed this at HoloViz meeting today and we are not really ready to recommend transition yet.

[Coderambling]

Ah I see, still interesting to know that that is the direction going forward.

[Coderambling]

Nice tutorial @MarcSkovMadsen ! Made 2 small comments, not vital.

[MarcSkovMadsen]

I would like to add Todo project using intermediate techniques. Here is my code. It almost works.

Code

from typing import Callable

import param

import panel as pn

pn.extension(sizing_mode="stretch_width", design="material")

BUTTON_WIDTH = 125

class Task(pn.viewable.Viewer):
    value: str = param.String()
    completed: bool = param.Boolean()
    
    remove: bool = param.Event()

    def __panel__(self):
        completed = pn.widgets.Checkbox.from_param(self.param.completed, name="", align="center", sizing_mode="fixed")
        content = pn.pane.Markdown(object=self.param.value)
        remove = pn.widgets.Button.from_param(self.param.remove, width=BUTTON_WIDTH, icon="trash", sizing_mode="fixed")
        return pn.Row(completed, content, remove, sizing_mode="stretch_width")

class TaskInput(pn.viewable.Viewer):
    value = param.ClassSelector(class_=Task)

    def _no_value(self, value):
        return not bool(value)

    def __panel__(self):
        text_input = pn.widgets.TextInput(name="Task", placeholder="Enter a task")
        text_input_has_value = pn.rx(self._no_value)(text_input.param.value_input)
        submit_task = pn.widgets.Button(
            name="Add",
            align="center",
            button_type="primary",
            width=BUTTON_WIDTH,
            sizing_mode="fixed",
            disabled=text_input_has_value,
        )
        
        @pn.depends(text_input, submit_task, watch=True)
        def clear_text_input(value, submit_task):
            if text_input.value:
                self.value = Task(value=text_input.value)
                text_input.value=text_input.value_input=""

        return pn.Row(
            text_input, submit_task
        )


class TaskList(pn.viewable.Viewer):
    tasks = param.List()

    remove_all_tasks = param.Event(label="Remove All")
    
    def __init__(self, **params):
        super().__init__(**params)
        for task in self.tasks:
            def remove(_, task=task):
                self.tasks = [item for item in self.tasks if not item==task]
            pn.bind(remove, task.param.remove, watch=True)
            pn.bind(self._handle_done_changed, task.param.completed, watch=True)

        self._llayout = pn.Column()

    def _remove_task(self, *args):
        task=args[0]
        self.tasks = [item for item in self.tasks if not item==task]
        
    def _remove_all_tasks(self, *args):
        self.clear()

    def _add_task(self, task):
        def remove(_, task=task):
                self.tasks = [item for item in self.tasks if not item==task]
        pn.bind(remove, task.param.remove, watch=True)
        self.tasks = [*self.tasks, task]

        return task

    @pn.depends("remove_all_tasks", watch=True)
    def _handle_remove_all_tasks(self):
        self.tasks=[]

    def _handle_done_changed(self, completed):
        self.param.trigger("tasks")

    @param.depends("tasks")
    def _layout(self):
        self._llayout[:]=self.tasks
        return self._llayout

    @param.depends("tasks")
    def status_report(self):
        total_tasks = len(self.tasks)
        completed_tasks = sum(task.completed for task in self.tasks)
        return f"{completed_tasks} of {total_tasks} tasks completed"

    @param.depends("tasks")
    def _has_tasks(self):
        return len(self.tasks)>0

    def __panel__(self):
        task_input = TaskInput()
        pn.bind(self._add_task, task_input.param.value, watch=True)
        clear = pn.widgets.Button.from_param(
            self.param.remove_all_tasks,
            button_type="primary",
            button_style="outline",
            width=BUTTON_WIDTH,
            sizing_mode="fixed",
            visible=self._has_tasks,
        )
        return pn.Column(
            "## WTG Task List",
            self.status_report,
            task_input,
            self._layout,
            pn.Row(pn.Spacer(), clear),
            max_width=500,
        )

tasks = [
    Task(value="Inspect the blades"),
    Task(value="Inspect the nacelle"),
    Task(value="Tighten the bolts"),
]

task_list = TaskList(tasks=tasks)

task_list.servable()

[philippjfr]

pre-commit.ci autofix

[philippjfr]

Once again merging as-is and following up with review in my final review (hopefully over the weekend).