Meaning of {.python}?

[maxdrohde]

I'm creating a reveal.js presentation for the first time, and I noticed this syntax in the examples:

```{.python}
1+2
```

which works, while the usual syntax without the . I've been using in HTML and PDF documents does not:

```{python}
1+2
```

giving me an error: ERROR: Invalid jupyter YAML metadata found in file (must be string or object)

How is {.python} different than {python} and when should I be using it?

[mcanouil]

Both are working properly for me.
The version with the dot is to output the content without evaluating it.
The following are completely equivalent:

```{.python}
1+2
```

```python
1+2
```

```{python}
#| echo: true
#| eval: false
1+2
```

[cscheid]

```{.python}
...
```

is the same as

```.python
...
```

which is the same as

```python
...
```

This is syntax directly from pandoc. A class declaration by itself has a shorthand without brackets (and a word by itself is shorthanded to a class declaration). The brackets are there to support attributes:

```{.python key1=value1 key2=value2}
...
```

This is different from

```{python}
...
```

Which quarto (and knitr) interpret as executable code cells. (Yes, this is moderately confusing.)

[eitsupi]

The current documentation is scattered with descriptions of code blocks, requiring users to read the website from cover to cover, I think...
(I remember reading somewhere about code blocks with {.python} so I looked on the website but could not find it...)

[cscheid]

@maxdrohde Can you share your full .qmd where you're getting a jupyter error? I want to make sure that isn't a bug.

[maxdrohde]

@cscheid Thanks for your explanation. I sorted out that issue -- was just an issue with my conda installation of python!

I think what confused me about the {.python} syntax is that it was difficult to find anything about it in the documentation, and the below section in the reveal.js guide made the distinction between executable and not-executable unclear.

https://quarto.org/docs/presentations/revealjs/#line-highlighting

[cscheid]

oof, that sure looks like a typo to me.

[cscheid]

Fixed now. Thanks for the report, and sorry for the confusion!