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-rwxr-xr-xrust-book/lifetimes/src/main.rs43
1 files changed, 43 insertions, 0 deletions
diff --git a/rust-book/lifetimes/src/main.rs b/rust-book/lifetimes/src/main.rs
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+++ b/rust-book/lifetimes/src/main.rs
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+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
+ // what this is doing is basically tagging x and y and the
+ // result with the same 'a, telling rust not to let any
+ // of them expire before the others; that way nothing
+ // will go out of scope prematurely and the result will
+ // always have a non-null reference
+
+ // basically, 'a gives all three values the same lifetime.
+ // so long as they're all alive at the same time, there are
+ // no reference errors
+
+ // note that the lifetime selected for the result is
+ // equal to the smaller of the lifetimes of the
+ // parameters
+
+ if x.len() > y.len() {
+ x
+ }
+ else {
+ y
+ }
+}
+
+struct ImportantExcerpt<'a> {
+ part: &'a str,
+}
+
+fn main() {
+ let string1 = String::from("abcd");
+ {
+ let string2 = "xyz";
+
+ let result = longest(string1.as_str(), string2);
+ //dbg!(result);
+ }
+
+ let script = String::from("Before time began, there was the cube. We know not where it comes from.");
+ let first_sentence = script.split('.')
+ .next()
+ .expect("Could not find a '.'");
+ let i = ImportantExcerpt { part: first_sentence };
+ dbg!(i.part);
+}