29 lines
660 B
Rust
29 lines
660 B
Rust
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use std::convert::TryFrom;
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use std::convert::TryInto;
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#[derive(Debug, PartialEq)]
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struct EvenNumber(i32);
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impl TryFrom<i32> for EvenNumber {
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type Error = ();
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fn try_from(value: i32) -> Result<Self, Self::Error> {
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if value % 2 == 0 {
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Ok(EvenNumber(value))
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} else {
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Err(())
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}
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}
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}
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fn main() {
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assert_eq!(EvenNumber::try_from(8), Ok(EvenNumber(8)));
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assert_eq!(EvenNumber::try_from(5), Err(()));
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let result: Result<EvenNumber, ()> = 8i32.try_into();
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assert_eq!(result, Ok(EvenNumber(8)));
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let result: Result<EvenNumber, ()> = 5i32.try_into();
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assert_eq!(result, Err(()));
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}
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