## Summary
Externally, development dependencies are currently structured as a flat
list of PEP 580-compatible requirements:
```toml
[tool.uv]
dev-dependencies = ["werkzeug"]
```
When locking, we lock all development dependencies; when syncing, users
can provide `--dev`.
Internally, though, we model them as dependency groups, similar to
Poetry, PDM, and [PEP 735](https://peps.python.org/pep-0735). This
enables us to change out the user-facing frontend without changing the
internal implementation, once we've decided how these should be exposed
to users.
A few important decisions encoded in the implementation (which we can
change later):
1. Groups are enabled globally, for all dependencies. This differs from
extras, which are enabled on a per-requirement basis. Note, however,
that we'll only discover groups for uv-enabled packages anyway.
2. Installing a group requires installing the base package. We rely on
this in PubGrub to ensure that we resolve to the same version (even
though we only expect groups to come from workspace dependencies anyway,
which are unique). But anyway, that's encoded in the resolver right now,
just as it is for extras.
In *some* places in our crates, `serde` (and `rkyv`) are optional
dependencies. I believe this was done out of reasons of "good sense,"
that is, it follows a Rust ecosystem pattern where serde integration
tends to be an opt-in crate feature. (And similarly for `rkyv`.)
However, ultimately, `uv` itself requires `serde` and `rkyv` to
function. Since our crates are strictly internal, there are limited
consumers for our crates without `serde` (and `rkyv`) enabled. I think
one possibility is that optional `serde` (and `rkyv`) integration means
that someone can do this:
cargo test -p pep440_rs
And this will run tests _without_ `serde` or `rkyv` enabled. That in
turn could lead to faster iteration time by reducing compile times. But,
I'm not sure this is worth supporting. The iterative compilation times
of
individual crates are probably fast enough in debug mode, even with
`serde` and `rkyv` enabled. Namely, `serde` and `rkyv` themselves
shouldn't need to be re-compiled in most cases. On `main`:
```
from-scratch: `cargo test -p pep440_rs --lib` 0.685
incremental: `cargo test -p pep440_rs --lib` 0.278s
from-scratch: `cargo test -p pep440_rs --features serde,rkyv --lib` 3.948s
incremental: `cargo test -p pep440_rs --features serde,rkyv --lib` 0.321s
```
So while a from-scratch build does take significantly longer, an
incremental build is about the same.
The benefit of doing this change is two-fold:
1. It brings out crates into alignment with "reality." In particular,
some crates were _implicitly_ relying on `serde` being enabled
without explicitly declaring it. This technically means that our
`Cargo.toml`s were wrong in some cases, but it is hard to observe it
because of feature unification in a Cargo workspace.
2. We no longer need to deal with the cognitive burden of writing
`#[cfg_attr(feature = "serde", ...)]` everywhere.
Address a few pedantic lints
lints are separated into separate commits so they can be reviewed
individually.
I've not added enforcement for any of these lints, but that could be
added if desirable.
First, replace all usages in files in-place. I used my editor for this.
If someone wants to add a one-liner that'd be fun.
Then, update directory and file names:
```
# Run twice for nested directories
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
# Update files
find . -type f -print0 | xargs -0 rename s/puffin/uv/g
```
Then add all the files again
```
# Add all the files again
git add crates
git add python/uv
# This one needs a force-add
git add -f crates/uv-trampoline
```
