using `value_repr` is clunky, as it forces me to think about document formatting

[sodiboo]

I want to create a numeric KDL entry with arbitrary precision (converting to KDL), like so:

let mut entry = KdlEntry::new(KdlValue::Float(0.0));
entry.set_format(KdlEntryFormat {
    value_repr: some_potentially_really_long_numeric_string,
    ..Default::default()
});

But, doing so actually doesn't work if i format my document, as autoformat() removes all formatting, including the value_repr, so all my values just become 0.0.

That's okay. I can tell autoformat not to touch this entry:

+ entry.keep_format()

But now, the generated document (after autoformatting) is no longer valid.

Error: 
  × Found invalid node name
    ╭─[10:37]
  9 │ }
 10 │ (development)config debug=#trueport=8080
    ·                                     ──┬─
    ·                                       ╰── not node name
    ╰────
  help: This can be any string type, including a quoted, raw, or multiline string, as well as a plain identifier string.

This is because autoformat() now keeps the value_repr, but for reasons that are beyond me it also keeps leading, which i didn't ever intend to touch.

kdl-rs/src/entry.rs

Lines 184 to 190 in 439aa63

	#[cfg(feature = "v1")]
	self.ensure_v2();
	self.format = self.format.take().map(|f| KdlEntryFormat {
	value_repr: f.value_repr,
	leading: f.leading,
	..Default::default()
	});

In the ensure_v1/ensure_v2 functions, there's this code, which seemingly acknowledges this issue:

kdl-rs/src/entry.rs

Lines 272 to 286 in 439aa63

	if let Some(value_repr) = value_repr.as_ref() {
	self.format = Some(
	self.format
	.clone()
	.map(|mut x| {
	x.value_repr = value_repr.into();
	x
	})
	.unwrap_or_else(|| KdlEntryFormat {
	value_repr: value_repr.into(),
	leading: " ".into(),
	..Default::default()
	}),
	)
	}

If there's no format on the node, and it sets the value_repr, it also sets the leading to a singular space.

But that branch is unreachable? This format.unwrap_or_else(...) is in an if statement, which runs if and only if the format is also Some(_).

So, in my code, i must copy this unreachable branch and set leading: " ".into(). But, i don't want to have to care about this.

I would expect KdlEntryFormat::default() to contain sensible values, like having a leading space (because, without any leading or trailing whitespace, a given KdlEntryFormat isn't valid inside of a full document). But, the format of an Entry shouldn't need to contain leading/trailing spaces to be valid. impl Display for KdlEntry actually doesn't behave weirdly at all on its own, even when there's empty leading/trailing formatting. The issue only occurs when stringifying a KdlNode. Currently, a space is inserted if and only if there is no explicit format set for the entry:

kdl-rs/src/node.rs

Lines 846 to 852 in 439aa63

	for entry in &self.entries {
	if entry.format().is_none() {
	write!(f, " ")?;
	}
	write!(f, "{}", entry)?;
	space_before_children = entry.format().is_none();
	}

A lot of places like this check for a single field of the format struct. It would perhaps make a lot more sense, given this usage, for every format field to be Option<T>. There's no way to specify "an entry with a specific value repr, but unspecified leading whitespace"; which is what i really want; i'd like all the implicit printing behaviour of adding leading spaces, please.

Also, the space before the children check here basically is always ignored, because, when creating a node, the format is Some(_) by default, which overrides the space_before_children check. With autoformatting, the space is explicitly inserted, so this quirk is easy to miss, unlike with KdlEntryFormat.leading which is not mitigated by autoformat.

---

I'm aware of #77, and i suppose this is a "duplicate"/subset of that issue; this is related to interaction with autoformat or more generally the formatting options. "it's completely borked right now" yeah i noticed.

But i want to use kdl-rs as a fully data-oriented KDL document builder without caring at all about formatting. I can almost do that with autoformat as-is. Most of its problems don't affect me at all, as my documents never contain comments, raw/multiline strings, etc.

If i don't care about numeric precision, kdl-rs is already usable like this. As soon as i try to set value_repr, i must start manually formatting. :(