mirror of
https://github.com/clap-rs/clap
synced 2024-09-21 06:41:54 +00:00
bfa02fd418
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"
37 lines
1.1 KiB
Rust
37 lines
1.1 KiB
Rust
use clap::{App, Arg};
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fn main() {
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let matches = App::new("myapp")
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// Application logic goes here...
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.arg(
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Arg::new("input")
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.help("the input file to use")
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.index(1)
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.required(true)
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// You can pass in a closure, or a function
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.validator(is_png),
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)
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.get_matches();
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println!(
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"The .PNG file is: {}",
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matches
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.value_of("input")
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.expect("'input' is required and parsing will fail if its missing")
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);
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}
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fn is_png(val: &str) -> Result<(), String> {
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// val is the argument value passed in by the user
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// val has type of String.
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if val.ends_with(".png") {
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Ok(())
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} else {
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// clap automatically adds "error: " to the beginning
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// of the message.
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Err(String::from("the file format must be png."))
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}
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// Of course, you can do more complicated validation as
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// well, but for the simplicity, this example only checks
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// if the value passed in ends with ".png" or not.
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}
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