<details><summary>Combinatoric example</summary>
```no_run
#[derive(Debug, Clone)]
pub struct Options {
verbose: bool,
release: bool,
default_features: bool,
}
pub fn options() -> OptionParser<Options> {
let verbose = short('v')
.long("verbose")
.help("Produce verbose output")
.switch();
let release = long("release")
.help("Build artifacts in release mode")
.flag(true, false);
let default_features = long("no-default-features")
.help("Do not activate default features")
// default_features uses opposite values,
// producing `true` when value is absent
.flag(false, true);
construct!(Options {
verbose,
release,
default_features,
})
.to_options()
}
fn main() {
println!("{:?}", options().run())
}
```
</details>
<details><summary>Derive example</summary>
```no_run
#[derive(Debug, Clone, Bpaf)]
#[bpaf(options)]
pub struct Options {
/// Produce verbose output
// bpaf uses `switch` for `bool` fields in named
// structs unless consumer attribute is present.
// But it is also possible to give it explicit
// consumer annotation to serve as a reminder:
// #[bpaf(short, long, switch)]
#[bpaf(short, long)]
verbose: bool,
#[bpaf(flag(true, false))]
/// Build artifacts in release mode
release: bool,
/// Do not activate default features
// default_features uses opposite values,
// producing `true` when value is absent
#[bpaf(long("no-default-features"), flag(false, true))]
default_features: bool,
}
fn main() {
println!("{:?}", options().run())
}
```
</details>
<details><summary>Output</summary>
In `--help` output `bpaf` shows switches as usual flags with no meta variable attached
<div class='bpaf-doc'>
$ app --help<br>
<p><b>Usage</b>: <tt><b>app</b></tt> [<tt><b>-v</b></tt>] [<tt><b>--release</b></tt>] [<tt><b>--no-default-features</b></tt>]</p><p><div>
<b>Available options:</b></div><dl><dt><tt><b>-v</b></tt>, <tt><b>--verbose</b></tt></dt>
<dd>Produce verbose output</dd>
<dt><tt><b> --release</b></tt></dt>
<dd>Build artifacts in release mode</dd>
<dt><tt><b> --no-default-features</b></tt></dt>
<dd>Do not activate default features</dd>
<dt><tt><b>-h</b></tt>, <tt><b>--help</b></tt></dt>
<dd>Prints help information</dd>
</dl>
</p>
<style>
div.bpaf-doc {
padding: 14px;
background-color:var(--code-block-background-color);
font-family: "Source Code Pro", monospace;
margin-bottom: 0.75em;
}
div.bpaf-doc dt { margin-left: 1em; }
div.bpaf-doc dd { margin-left: 3em; }
div.bpaf-doc dl { margin-top: 0; padding-left: 1em; }
div.bpaf-doc { padding-left: 1em; }
</style>
</div>
Both `switch` and `flag` succeed if value is not present, `switch` returns `false`, `flag` returns
second value.
<div class='bpaf-doc'>
$ app <br>
Options { verbose: false, release: false, default_features: true }
</div>
When value is present - `switch` returns `true`, `flag` returns first value.
<div class='bpaf-doc'>
$ app --verbose --no-default-features --detailed<br>
<b>Error:</b> <b>--detailed</b> is not expected in this context
<style>
div.bpaf-doc {
padding: 14px;
background-color:var(--code-block-background-color);
font-family: "Source Code Pro", monospace;
margin-bottom: 0.75em;
}
div.bpaf-doc dt { margin-left: 1em; }
div.bpaf-doc dd { margin-left: 3em; }
div.bpaf-doc dl { margin-top: 0; padding-left: 1em; }
div.bpaf-doc { padding-left: 1em; }
</style>
</div>
Like with most parsrs unless specified `switch` and `flag` consume at most one item from the
command line:
<div class='bpaf-doc'>
$ app --no-default-features --no-default-features<br>
<b>Error:</b> argument <tt><b>--no-default-features</b></tt> cannot be used multiple times in this context
<style>
div.bpaf-doc {
padding: 14px;
background-color:var(--code-block-background-color);
font-family: "Source Code Pro", monospace;
margin-bottom: 0.75em;
}
div.bpaf-doc dt { margin-left: 1em; }
div.bpaf-doc dd { margin-left: 3em; }
div.bpaf-doc dl { margin-top: 0; padding-left: 1em; }
div.bpaf-doc { padding-left: 1em; }
</style>
</div>
</details>