mirror of
https://github.com/clap-rs/clap
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35 lines
1.5 KiB
Rust
35 lines
1.5 KiB
Rust
use clap::{App, AppSettings};
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fn main() {
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// You can use AppSettings to change the application level behavior of clap. .setting() function
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// of App struct takes AppSettings enum as argument. There is also .settings() function which
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// takes slice of AppSettings enum. You can learn more about AppSettings in the documentation,
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// which also has examples on each setting.
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//
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// This example will only show usage of one AppSettings setting. See documentation for more
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// information.
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let matches = App::new("myapp")
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.setting(AppSettings::SubcommandsNegateReqs)
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// Negates requirement of parent command.
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.arg("<input> 'input file to use'")
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// Required positional argument called input. This
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// will be only required if subcommand is not present.
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.subcommand(App::new("test").about("does some testing"))
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// if program is invoked with subcommand, you do not
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// need to specify the <input> argument anymore due to
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// the AppSettings::SubcommandsNegateReqs setting.
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.get_matches();
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// Calling unwrap() on "input" would not be advised here, because although it's required,
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// if the user uses a subcommand, those requirements are no longer required. Hence, we should
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// use some sort of 'if let' construct
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if let Some(inp) = matches.value_of("input") {
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println!("The input file is: {}", inp);
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}
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match matches.subcommand() {
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("test", _) => println!("The 'test' subcommand was used"),
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_ => unreachable!(),
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}
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}
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