81 lines
1.7 KiB
Rust
81 lines
1.7 KiB
Rust
use std::fmt::Display;
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struct Pair<T> {
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x: T,
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y: T,
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}
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impl<T> Pair<T> {
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fn new(x: T, y: T) -> Self {
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Self {
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x,
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y,
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}
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}
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}
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// Only implements method if both traits are satisfied
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impl<T: Display + PartialOrd> Pair<T> {
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fn cmp_display(&self) {
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if self.x >= self.y {
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println!("The largest member is x = {}", self.x);
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} else {
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println!("The largest member is y = {}", self.y);
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}
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}
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}
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pub trait Summary {
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fn summarize_author(&self) -> String;
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// default implementation
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fn summarize(&self) -> String {
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String::from("(Read more...)")
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}
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}
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pub struct NewsArticle {
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pub headline: String,
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pub location: String,
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pub author: String,
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pub content: String,
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}
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impl Summary for NewsArticle {
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fn summarize_author(&self) -> String {
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self.author.to_string()
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}
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fn summarize(&self) -> String {
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format!("{}, by {} ({})", self.headline, self.author, self.location)
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}
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}
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pub struct Tweet {
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pub username: String,
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pub content: String,
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pub reply: bool,
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pub retweet: bool,
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}
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// Uses default implementation for summarize method
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impl Summary for Tweet {
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fn summarize_author(&self) -> String {
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format!("@{}", self.username)
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}
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}
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pub fn returns_summarizable() -> impl Summary {
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Tweet {
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username: String::from("horse_ebooks"),
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content: String::from("of course, as you probably already know, people"),
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reply: false,
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retweet: false,
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}
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}
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// Function/method requiring a trait's implementation
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// pub fn notify(item: impl Summary) {
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// println!("Breaking news! {}", item.summarize());
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// }
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