Improve Drop description (src/ch15-03-drop.md) #4181
Description
Hello guys!
TLDR: my main idea is to provide something more obvious than just println!("Dropping CustomSmartPointer with data {}!", self.data);. For instance, when we are talking about files, the current book chapter states that "...lets you customize what happens when a value is about to go out of scope.", but it doesn't really show any customization behavior. So I thought it might be helpful for newcomers to see that drop() could be useful when working with fixtures, so you don't need to write a function fn clear_data() and call it manually after every test - you can just extend drop behavior.
I thought about something like this + description:
use std::fs::File;
use std::path::PathBuf;
struct TempFile {
file: File,
path: PathBuf,
}
impl TempFile {
fn new(path: PathBuf) -> std::io::Result<Self> {
Ok(Self {
file: File::create(&path)?,
path,
})
}
}
impl Drop for TempFile {
fn drop(&mut self) {
// Clean up the file when it's no longer needed
if let Err(e) = std::fs::remove_file(&self.path) {
eprintln!("Failed to remove temp file: {}", e);
}
println!("Dropped");
}
}
fn main() -> std::io::Result<()> {
let temp = TempFile::new("test.txt".into())?;
// Work with temp.file here
// The file will be automatically deleted when temp goes out of scope
Ok(())
}
// OR
#[test]
fn test_with_temp_file() {
let temp = TempFile::new("test.txt".into()).unwrap();
// print "Dropped"
}What do you think? The example of course could be improved or changed, but what about the principal idea?
PS: I don't think this description belongs in the standard library docs (https://github.com/rust-lang/rust/blob/master/library/core/src/mem/mod.rs#L940) since this behavior is obvious, but I think it could be useful for The Rust Book.