1 unstable release
0.1.0 | Jun 19, 2020 |
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#15 in #variant-name
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Used in oq3_semantics
8KB
71 lines
boolenum
BoolEnum
is a derive macro to create ergonomic boolean enums with less boilerplate.
It generates From<bool>
, Into<bool>
and Not
impls for your enum.
use boolenum::BoolEnum;
// Variant names can be Yes and No (in any order) ...
#[derive(BoolEnum)]
enum UseColors {
No,
Yes,
}
// or True and False
#[derive(BoolEnum)]
enum ShowExpired {
True,
False,
}
fn print_things(use_colors: UseColors, show_expired: ShowExpired) {
if use_colors.into() { // Into<bool>
// ...
}
}
fn main() {
print_things(UseColors::Yes, ShowExpired::False)
}
Boolean enums are useful for differentiating between boolean arguments to a function,
so you can write something like encode(&bytes, Encrypt::Yes, Compress::No)
instead of encode(&bytes, true, false)
.
Goes well with structopt, for type-safe handling of command-line flags:
use boolenum::BoolEnum;
use structopt::StructOpt;
#[derive(BoolEnum)]
enum Verbose { No, Yes }
#[derive(BoolEnum)]
enum Colors { No, Yes }
#[derive(StructOpt)]
struct Opt {
#[structopt(short, long, parse(from_flag))]
verbose: Verbose, // works because Verbose implements From<bool>
#[structopt(short, long, parse(from_flag))]
colors: Colors,
}
fn main() {
let opt = Opt::from_args();
do_thing(opt.verbose, opt.colors);
}
fn do_thing(verbose: Verbose, colors: Colors) {
if verbose.into() { }
if colors.into() { }
}
BoolEnum
works on enums with two unit variants, named either Yes and No, or True and False. The order of the variants in the enum doesn't matter.
License: MIT OR Apache-2.0
Dependencies
~1.5MB
~36K SLoC