clap/examples/10_default_values.rs
Ed Page bfa02fd418 test: More thoroughly test examples
This ports our example testing over to [trycmd](https://docs.rs/) so
we can:
- More thoroughly test our examples
- Provide always-up-to-date example usage

The old way of testing automatically picked up examples.  This new way
requires we have a `.md` file that uses the example in some way.

Notes:
- Moved overall example description to the `.md` file
- I added cross-linking between related examples
- `14_groups` had a redundant paragraph (twice talked about "one and
  only one"
2021-11-23 13:13:41 -06:00

30 lines
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Rust

use clap::{App, Arg};
fn main() {
let matches = App::new("myapp")
.about("does awesome things")
.arg(
Arg::new("INPUT")
.help("The input file to use")
.default_value("input.txt")
.index(1),
)
// Next we'll use the Option::unwrap_or method on this "CONFIG" option
.arg(
Arg::new("CONFIG")
.help("The config file to use")
.short('c')
.takes_value(true),
)
.get_matches();
let input = matches
.value_of("INPUT")
.expect("'INPUT' is default and parsing will ensure there always is a value");
// Using Option::unwrap_or we get the same effect, but without the added help text injection
let config_file = matches.value_of("CONFIG").unwrap_or("config.json");
println!("The input file is: {}", input);
println!("The config file is: {}", config_file);
}