develop_editor.md

Develop in an Editor

In this section you will learn more advances techniques to develop efficiently in an editor:

• Resetting the cache with pn.state.clear_caches() or some_cached_func.clear().

• Debug with Pdb by inserting a breakpoint()

:::{note} This guide builds upon the Develop in an Editor (beginner) tutorial. :::

:::{note} Some of the features demonstrated in this guide might require special configuration of your editor. For configuration we refer you to the Resources section below and general resources on the web. :::

Resetting the Cache

When developing with the --dev option and utilizing caching, you may need to reset the cache. You have the option to clear either the entire cache or just the cache for a specific function.

Execute the code below:

import panel as pn
from datetime import datetime

pn.extension()

# To clear the entire cache, uncomment the following line:
# pn.state.clear_caches()

@pn.cache
def get_data():
    return datetime.now()

# To clear the cache for this specific function, uncomment:
# get_data.clear()

pn.panel(get_data).servable()

To reset the cache, uncomment and use either pn.state.clear_caches() for the entire cache or get_data.clear() for the specific function's cache. Below is a video demonstrating this process:

Your browser does not support the video tag.

Debug your App with Pdb

A simple way to debug your apps that works in any editor is to insert a breakpoint().

Copy the code below into a file named app.py.

import panel as pn

pn.extension(design="material")

def handle_click(event):
    breakpoint()

pn.widgets.Button(name="Click Me", on_click=handle_click, button_type="primary").servable()

Serve the app with panel serve app.py --dev.

Open http://localhost:5006/app in a browser.

The app will look something like

Click the Click Me Button.

Your terminal will look something like

$ panel serve app.py --dev
2024-01-20 08:12:09,512 Starting Bokeh server version 3.3.3 (running on Tornado 6.4)
2024-01-20 08:12:09,514 User authentication hooks NOT provided (default user enabled)
2024-01-20 08:12:09,516 Bokeh app running at: http://localhost:5006/app
2024-01-20 08:12:09,516 Starting Bokeh server with process id: 9768
2024-01-20 08:12:10,608 WebSocket connection opened
2024-01-20 08:12:10,608 ServerConnection created
--Return--
> /home/jovyan/app.py(6)handle_click()->None
-> breakpoint()
(Pdb)

Write event in the terminal. Press ENTER.

It should look like

Write help and press ENTER for more info. It will look like

(Pdb) help

Documented commands (type help <topic>):
========================================
EOF    c          d        h         list      q        rv       undisplay
a      cl         debug    help      ll        quit     s        unt
alias  clear      disable  ignore    longlist  r        source   until
args   commands   display  interact  n         restart  step     up
b      condition  down     j         next      return   tbreak   w
break  cont       enable   jump      p         retval   u        whatis
bt     continue   exit     l         pp        run      unalias  where

Miscellaneous help topics:
==========================
exec  pdb

Write c and press ENTER to continue running the code and server.

:::{note} For more about debugging with Pdb and breakpoint please check out the PDB Documentation. :::

:::{note} For integrated debugging in your editor, please refer to the Resources section below and general resources on the web. :::

Recap

You have learned to

• Reset the cache with pn.state.clear_caches() or some_cached_func.clear().

• Debug with Pdb by inserting a breakpoint()

Resources

Tutorials

• Develop in an Editor (Beginner)

Explanation

• Develop Seamlessly

How-to

• Configure PyCharm

• Configure VS Code