---
title: Executable code snippets in docs and HTML object representations
layout: post
excerpt: "It just looks so nice."
assets: /assets/blog/executable-code-snippets-in-docs-and-html-object-representations
thumbnail: /assets/blog/executable-code-snippets-in-docs-and-html-object-representations/thumbnail.png
social_image: /assets/blog/executable-code-snippets-in-docs-and-html-object-representations/thumbnail.png
alt: |
A screenshot of a tree diagram created using unicode bar characters. It starts at "root" and then fans out to "class=od" and class="rd" which themselves fan out to "expver=0001" and "expver=0002" and finally "param=1" and "param=2".
image_class: invertable
---
Just a quick one. Lately I've started writing the documention for [a new software project involving trees](https://qubed.readthedocs.io).
While debugging that in a Jupyter notebook I made a small HTML representation of the tree that mimis the output of `tree` but using the HTML details tag so you can open and close the subtrees.
This works using by giving the object a "_repr_html_" method that returns a HTML string. If it's present, Jupyter notebooks will use the output of that instead of `repr` to display a rich version of the object in a notebook.
```python
class Title():
def __init__(self, x):
self.x = x
def _repr_html_(self):
return f"
{self.x}
"
```
I then set up executable code snippets in these docs so I could give code examples and not have to paste the output in myself. I'm using MyST-NB in sphinx to do this, it gives you a nicely syntax highlighted code block along with the output evaluated against the actual code. Since the NB in Myst-NB stands for notebook, it's perhaps not so surprising that the HTML inline output also works!
The overall effect looks a bit like the below but see it [in place](https://qubed.readthedocs.io) for a better idea of how it looks with proper CSS.
```python
from qubed import Qube
q = Qube.from_dict({
"class=od" : {
"expver=0001": {"param=1":{}, "param=2":{}},
"expver=0002": {"param=1":{}, "param=2":{}},
},
"class=rd" : {
"expver=0001": {"param=1":{}, "param=2":{}, "param=3":{}},
"expver=0002": {"param=1":{}, "param=2":{}},
},
})
# depth controls how much of the tree is open when rendered as html.
q.html(depth=100)
```