knitr/quarto rendering does not capture certain Julia output with user-defined show method

[paciorek]

I'm having some Julia output not captured in the generated document by knitr/quarto, which makes me think there might be something that needs to be fixed in terms of capturing certain output from Julia.

Here's my qmd content:

---
title: test
engine: knitr
---

```{julia}
struct test
  x
end

function Base.show(io::IO, x::test)
  println("hello")
end

y = test("foo");
y

z = 35;
z
```

In my rendered output (either from knit2html("test.qmd") or quarto render test.qmd), I do not see "hello" in the rendered output, which should be printed out when invoking y. But I do see 35 from invoking z, which makes it seem like certain output from Julia is treated differently because of my user-defined show method.

Instead "hello" is printed to the (R or bash) console during the rendering process:

> knitr::knit2html("test.qmd")


processing file: test.qmd
  |....................................................| 100% [unnamed-chunk-1]hello
                                                                                                           
output file: test.md

I think this may relate to issue #76.

This is with R 4.4.0 and JuliaCall 0.17.6 and knitr 1.46 or 1.48, under both MacOS and Linux.