I've been thinking it'd be simpler to introduce `dyn Trait` via `&dyn
Trait` rather than waiting for the smart pointers section and `Box<dyn
Trait>`. This PR adds a slide to the Generics section that introduces
`&dyn Trait` and compares it to `&impl Trait`, juxtaposing
monomorphization and static dispatch against type-erasure and dynamic
dispatch. I've then updated the existing trait object slide to call back
to the earlier introduction, and call out that using `Box<dyn Trait>`
gives you an owned trait object rather than a borrowed one.
I was a bit dissatisfied with the test code for the generic min
exercise. We were supposed to be testing that the student wrote the
generic function correctly, but we only test their `min` function with
one type. I rewrote the exercise to test against multiple types, which
required that we use the regular `Ord` trait rather than a custom one. I
tend to prefer using the real items from `std` when we can because it's
a good way to get students familiar with the standard library. I also
removed the custom `Citation` type since it wasn't really important to
the exercise.
Based on feedback from @marshallpierce that mornings took about 2.5
hours, this adjusts a bunch of the morning times downward to try to
match that. In other words, this is trying to make the times in the
course more accurate, rather than reducing the amount of time available
for these slides.
This also updates the `course-schedule` tool to be able to show
per-segment timings.
This is the result of running `dprint fmt` after removing `src/` from
the list of excluded directories.
This also reformats the Rust code: we might want to tweak this a bit in
the future since some of the changes removes the hand-formatting. Of
course, this formatting can be seen as a mis-feature, so maybe this is
good overall.
Thanks to mdbook-i18n-helpers 0.2, the POT file is nearly unchanged
after this, meaning that all existing translations remain valid! A few
messages were changed because of stray whitespace characters:
msgid ""
"Slices always borrow from another object. In this example, `a` has to remain "
-"'alive' (in scope) for at least as long as our slice. "
+"'alive' (in scope) for at least as long as our slice."
msgstr ""
The formatting is enforced in CI and we will have to see how annoying
this is in practice for the many contributors. If it becomes annoying,
we should look into fixing dprint/check#11 so that `dprint` can annotate
the lines that need fixing directly, then I think we can consider more
strict formatting checks.
I added more customization to `rustfmt.toml`. This is to better emulate
the dense style used in the course:
- `max_width = 85` allows lines to take up the full width available in
our code blocks (when taking margins and the line numbers into account).
- `wrap_comments = true` ensures that we don't show very long comments
in the code examples. I edited some comments to shorten them and avoid
unnecessary line breaks — please trim other unnecessarily long comments
when you see them! Remember we're writing code for slides 😄
- `use_small_heuristics = "Max"` allows for things like struct literals
and if-statements to take up the full line width configured above.
The formatting settings apply to all our Rust code right now — I think
we could improve this with https://github.com/dprint/dprint/issues/711
which lets us add per-directory `dprint` configuration files. However,
the `inherit: true` setting is not yet implemented (as far as I can
tell), so a nested configuration file will have to copy most or all of
the top-level file.
I've taken some work by @fw-immunant and others on the new organization
of the course and condensed it into a form amenable to a text editor and
some computational analysis. You can see the inputs in `course.py` but
the interesting bits are the output: `outline.md` and `slides.md`.
The idea is to break the course into more, smaller segments with
exercises at the ends and breaks in between. So `outline.md` lists the
segments, their duration, and sums those durations up per-day. It shows
we're about an hour too long right now! There are more details of the
segments in `slides.md`, or you can see mostly the same stuff in
`course.py`.
This now contains all of the content from the v1 course, ensuring both
that we've covered everything and that we'll have somewhere to redirect
every page.
Fixes#1082.
Fixes#1465.
---------
Co-authored-by: Nicole LeGare <dlegare.1001@gmail.com>
Co-authored-by: Martin Geisler <mgeisler@google.com>
* don't explain default trait methods early
* talk about Iterator before IntoIterator
* Defer discussion of trait objects to that chapter
* be more specific about turbofish, in speaker notes
