add incomplete notes on code style

This commit is contained in:
Connor Olding 2022-09-23 12:14:00 -07:00
parent a11d3fa9f4
commit c490e26fb9

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@ -44,3 +44,79 @@ this project must be built on a host running Linux.
if you are not running Linux, use a VM of some sort.
i personally use VirtualBox running Alpine Linux.
i have not tried building with WSL2.
### Code Style
this project encourages a heretical and horrifying style of code
for its shell scripts. the intent is to chain `&&`s while facilitating
trivial re-ordering of lines. for instance, a `RUN` command in a Dockerfile
(which just executes a line of shell) might look like this:
```sh
RUN : \
&& echo hello \
&& note() \
{ : \
&& printf '\033[1m%s\033[m: %s\n' >&2 \
noted "$*" \
;} \
&& note '\\( o _ o )//' \
;
```
*gratuitous explanation:*
* 4-space indentation is a must, since at least three characters
are needed to contain the operators on the left of each line.
* `:` is akin to the `true` command; it's used as a no-op
that only sets the most recent exit code (`$?`) to `0`.
* `\` continues the code to the next line;
the proceeding newline is removed and ignored.
this is purely superficial.
* `&&` is a short-circuiting operator that only evaluates
its right-hand side when `$?` is `0`. `&&` is preferred
over a simple semicolon because most programs use a
non-zero exit code to indicate that an error occurred,
whereas `;` will continue executing code,
even in the presence of an error.
* `||` is like `&&` but only executes when `$?` is *not* `0`.
**important:** `||` has a lower precedence than `&&`!
make sure to wrap your `||`s in braces unless you want to
capture *everything* before it. for instance:
` && { test -e myfile || touch myfile ;} \`
* leftmost `&&`s and `||`s are always centered within their 4-space indent.
* avoid using pipes (`|`) when possible, because only the
exit code of the final command in any pipe is respected.
* functions are declared (`()`) on their own line
without any braces or other commands.
* `{ :` is used to begin a multi-line block,
similar to how `RUN :` begins a shell command.
sadly, the space between the brace and the colon is not optional.
* ';}` is used to finish a multi-line block.
this is aligned with the preceeding `&&` and `||` operators.
thankfully, the space between `;` and `}` is optional.
* a final `;` is used to finish off the line-continutation.
this means that every line before it can end with a `\`,
which simplifies editing. when podman gives you strange errors,
double-check that you aren't forgetting the final semicolon.
* redirections are usually specified *before* a final list of arguments.
this makes skimming code easier when arguments extend across many lines.
* **TODO:** explain `if cmd ␤ ;then : ␤ ;fi`.
* **TODO:** explain `for cmd ␤ ;do : ␤ ;done`.
* **TODO:** explain `while cmd ␤ ;do : ␤ ;done`.
* **TODO:** explain `test`s.