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This commit is contained in:
edgul
2026-07-25 17:10:06 -04:00
parent 0eba3cfa29
commit 0e297a9fe6
6 changed files with 193 additions and 30 deletions
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Cargo.lock
Generated
+144
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@@ -2,6 +2,150 @@
# It is not intended for manual editing.
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Cargo.toml
+1
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@@ -4,3 +4,4 @@ version = "0.1.0"
edition = "2024"
[dependencies]
futures = "0.3.32"
src/arrays.rs
+2 -1
View File
@@ -1,4 +1,5 @@
#[derive(Debug, PartialEq)]
#[allow(dead_code)]
pub struct EmptyListError;
// implementing Error for my error to satisfy Box<dyn std::error::Error>
@@ -15,6 +16,7 @@ impl std::fmt::Display for EmptyListError {
// Result<...,Box<dyn std::error::Error>> is overkill
// this is intuitive enough for caller error detection
// actually probably should use Option instead, but this is better for extension
#[allow(dead_code)]
pub fn min_and_max(list: &[u32]) -> Result<(u32, u32), EmptyListError> {
if list.is_empty() {
return Err(EmptyListError);
@@ -62,6 +64,5 @@ mod tests {
let r = &s;
println!("{}", *r); // works because there is no implicit move
// let thing = *r; // doesn't work because String does not implement Copy trait
}
}
src/async_play.rs
+22
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@@ -0,0 +1,22 @@
use std::{thread, time};
#[allow(dead_code)]
async fn do_something(number: i8) -> i8 {
println!("number {} is running", number);
let two_seconds = time::Duration::new(2, 0);
thread::sleep(two_seconds);
return 2;
}
#[cfg(test)]
mod tests {
use super::*; // need access to functions above
#[test]
fn test_async() {
let _ = async {
do_something(2).await;
};
assert!(true);
}
}
src/main.rs
+3 -4
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@@ -1,6 +1,7 @@
mod string;
mod arrays;
mod async_play;
mod fmt_debug;
mod string;
// when a String is passed to this function a move occurs:
// BUT only the stack allocation (ptr, len, cap) is copied over
@@ -74,7 +75,7 @@ fn min_and_max(list: &[u32]) -> Result<(u32, u32), EmptyListError> {
}
fn main() {
println!("Hello, world!");
println!("Learning Rust");
fmt_debug::test_report();
let s = String::new(); // no heap allocation until we add characters (capacity > 0)
@@ -112,6 +113,4 @@ fn main() {
let _s6 = String::from(s_lit); //underlying data copied to heap
// todo: Cow
println!("Learning Rust");
}
src/string.rs
+6 -10
View File
@@ -1,4 +1,4 @@
use std::rc::Rc;
//use std::rc::Rc;
// when a String is passed to this function a move occurs:
// BUT only the stack allocation (ptr, len, cap) is copied over
@@ -7,16 +7,12 @@ use std::rc::Rc;
// Why do we call it a "move"?
// A move indicates ownership transfer, not data transfer
#[allow(dead_code)]
fn takes_string(_s: String) {
}
fn takes_string(_s: String) {}
// You can do this, but you probably want &str
// UNLESS you want `&mut String`
#[allow(dead_code)]
fn takes_string_ref(_s: &String) {
}
fn takes_string_ref(_s: &String) {}
// Compilation error and warning:
// rustc: the size for values of type `str` cannot be known at compilation time
@@ -36,9 +32,7 @@ fn takes_string_ref(_s: &String) {
// this is fine because now the variable is a fat pointer: pointer + length
// it's the length aspect that makes us abot to work on the str
#[allow(dead_code)]
fn takes_str_ref(_s: &str) {
}
fn takes_str_ref(_s: &str) {}
// yeah, we can do this
fn _get_static_str() -> &'static str {
@@ -49,6 +43,8 @@ fn _get_static_str() -> &'static str {
// and run the test code only when you run cargo test, not when you run cargo build
#[cfg(test)]
mod tests {
use std::rc::Rc;
use super::*; // need access to functions above
#[test]