## Motivation
Currently, most crates in this repository have `examples` directories
that contain demonstrations of how to use that crate. In many cases,
these examples also use APIs from _other_ crates in this repository ---
for example, the `tracing-subscriber` `FmtSubscriber` is used by many
examples to format the output generated by instrumentation APIs, so that
users can see the generated output.
The disadvantage to this approach is that it requires crates in this
repository to have dev-dependencies on each other. This is problematic
for a few reasons:
* It makes it easy to inadvertently create cyclic dependencies between
`tracing` crates.
* When building a crate that depends on a crate with dev-dependencies,
those dev-dependencies are downloaded and compiled, despite not being
linked into the dependent crate. This means that users depending on a
tracing crate will pull in a larger dependency tree, since the
dev-dependencies used by examples are also downloaded, although they
are not required by the dependent. This makes the tracing crate
appear to be a much larger dependency than it actually is, and can
make users' build times slower.
* Finally, it means that the examples are scattered throughout the
repository. In some cases, the examples demonstrate the functionality
of multiple crates, but only live in one crate's `examples` dir. This
can hurt the discoverability of the examples, especially for new
users.
## Solution
This branch moves all the examples out of individual crates and into a
new `examples` crate (which is otherwise empty and cannot be published
to crates.io). The `examples` crate is part of the root `tracing`
workspace, so it's still possible to `cargo run --example WHATEVER`.
Similarly, `cargo test --all` will still build the examples.
All dev-dependencies which were only required by examples and not tests
have been removed, which has a drastic impact on the dependency
footprint of some crates.
Finally, I've added a README to the `examples` crate, listing the
available examples and what functionality they demonstrate.
Refs: #315, #308
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
