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use clap::{crate_authors, crate_description, crate_name, crate_version, App, Arg};
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macro_rules! scale_message {
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($n:ident) => {
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Err(format!("<{}> is not a positive integer", $n))
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};
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}
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fn main() {
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let matches = App::new(crate_name!())
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.version(crate_version!())
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.author(crate_authors!())
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.about(crate_description!())
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.arg(
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Arg::with_name("scale")
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.short("s")
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.long("scale")
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.help("The scale parameter for the object")
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.takes_value(true)
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.multiple(false)
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.value_name("N")
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.validator(|n: String| -> Result<(), String> {
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match n.parse::<i32>() {
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Ok(x) => {
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if x > 0 {
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Ok(())
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} else {
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scale_message!(n)
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}
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}
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Err(_) => scale_message!(n),
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}
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}),
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)
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.get_matches();
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let scale = matches.value_of("scale").map(|s| s.parse::<i32>().unwrap());
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println!("Scale was read and is <{}>", scale.unwrap_or(1));
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}
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