Reported in

• knitr engine with python: output option ignored for object with _repr_html_ method quarto-dev/quarto-cli#9389

and full example at

• Table output cannot be suppressed in Quarto when R code chunk present posit-dev/great-tables#291

Problem

Currently, results = 'hide' does not seem to be handled by reticulate's knitr engine. Example:

---
title: "Test report"
output: html_document
---

```{r, results = 'hide'}
class MyClass:
    def _repr_html_(self):
        return "<p>uh-oh</p>"

MyClass()
```

The results will still be shown. This is a minimal example - see posit-dev/great-tables#291 for one with great_tables

Context

This is because _repr_html_ is catched to be returned as a knitr::raw_html()

By returning engine_output(out = ), knitr's assumes the output is already filtered with what should be filtered.
Otherwise, it will be handled directly engine_output() default usage
https://github.com/yihui/knitr/blob/ba8d9fb0ecd60f3f9ebec58fdde1e689bdc40ad3/R/engine.R#L96-L98

So I do think reticulate needs to support results = 'hide' and not provide outputs in the list when the option is provided.

I can make a PR - just need to think about the best place to do this.