UIs in Python

1.1 Web toolkits talking to python servers

One obvious use-case for all this evented stuff is to use the great GUI mind-share of our time, web engines talking to servers. The details of doing this oneself are tricky on both the client side and the server side. I would tend not to touch either of them myself because I have specialised my skillset elsewhere. Instead, I would use one of the fancy new dashboard systems that have arisen in the last couple of years. For exploratory data analysis and visualisation, these are pretty good and mostly python.

For other purposes, you might roll your own. Below are some systems I have used unsuccessfully to that end in the past.

Flexx attempts to provide more bells and whistles, including automatic widget generation and synchronisation from python, still using asyncio.

Thrust renders a chromium window to look at your served code. I’m not 100% clear how it is substantially easier than just running a browser and a server.

brython interprets python using javascript.

There are many examples of rolling your own, using a classic webserver, or electron. Your adventure continues at javascript apps.

1.2 Gradio

Targeting ML uses: Gradio “…is the fastest way to demo your machine learning model with a friendly web interface so that anyone can use it, anywhere!”

Limited in scope but well-supported.

• Introduction to Gradio
• gradio-app/gradio: Create UIs for your machine learning model in Python in 3 minutes
• oobabooga/text-generation-webui: A gradio web UI for running Large Language Models like GPT-J 6B, OPT, GALACTICA, LLaMA, and Pygmalion.

1.3 Bizarre hybrids of Web GUIs and user interfaces

DIY python web gui by David Baird:

In this howto, I explain the following concepts:

• How to launch a GUI toolkit in a separate thread, and how to communicate with this thread.

• How to embed a web browser inside the GUI, and how to communicate with this embedded web browser without using sockets. By not using sockets, we don’t have to worry about socket security, and we don’t have to worry about allocating a socket. […] In other words, we will have AJAX-like […] functionality to communicate with Python but without actually having to use AJAX.

2.1 RAD/gui builders

• wxformbuilder
• wxglade

2.2 macOS Framework python

You are getting errors like This program needs access to the screen. Please run with a Framework build of python, and only when you are logged in on the main display of your Mac.

This probably means your python virtual environment is not a framework python virtualenv. What is a “framework python”? It’s highly unlikely you are being paid enough to care what a framework build of python is. I certainly am not.

You can work around it with laborious wrapper hacks, or use anaconda python

conda install python.app
pythonw

or your system python.

For python 3 you can use the native virtual environment, venv, now a built-in virtual python environment system in python 3. It doesn’t support python 2 but fixes various problems, e.g. supporting macOS Framework python and is covered by the python docs in the python virtual environment introduction.

If there are other solutions and they are one iota more complex than this I don’t want to hear about them thanks.

3.1 Cute examples

It looks primitive, but you can get a long way.

E.g. dynamic collapsible content:

def toggle(self):
    if bool(self.show.get()):
      self.sub_frame.pack(fill="x", expand=1)
      self.toggle_button.configure(text='-')
    else:
      self.sub_frame.forget()
      self.toggle_button.configure(text='+')

Or see snake, including sprites and canvas with collision detection.

There is an even-simpler GUI thing called EasyGUI which attempts to make GUI code less awkward. I think it is mostly about modal boxes and is not as smooth for visualisation of information.

3.2 intros

• tkdocs is an incomplete but pretty good book on tkinter, also explaining the perl and ruby versions
• effbot tkinter guide is good and differently incomplete and slightly outdated.
• See Tkinter example for controlling a robot
• NMT Tkinter reference is in-depth but outdated, missing many renames. Still the best, IMO.
• The official tk docs are complete, but referencey and written for tcl rather than python.
• the official python tkinter docs are fine but especially incomplete.

3.3 tips

• For sorta-native look and feel you use ttk which introduces styles and themes. Neither of these are obvious.
• Control variables provide convenient data-syncing accessors for what I will loosely call “scalar types”. Think of them as primitive controllers.
• There are two layout managers, pack and grid. If you come from an HTML background the former is somewhat like a mildly crippled version of block-layout and the latter somewhat more like HTML tables. You can’t mix them within a single parent widget, but you can freely nest Frame widgets with different interior layouts.