26.5 Drop

[njr0]

I thought you missed a trick here. I think the point is made more strongly if you either don't drop(a) at the end or create another variable that you don't drop. I changed it to:

fn main() {
    let a = Droppable { name: "a" };
    let aa = Droppable {name: "aa"};
    {
        let b = Droppable { name: "b" };
        {
            let c = Droppable { name: "c" };
            let d = Droppable { name: "d" };
            println!("Exiting block B");
        }
        println!("Exiting block A");
    }
    drop(a);
    println!("Exiting main");
}

so it prints

Exiting block B  
Dropping d  
Dropping c  
Exiting block A  
Dropping b  
Dropping a  
Exiting main  
Dropping aa

which seems to make the point more strongly, to me.

[djmitche]

Rather than adding a new variable, maybe we should remove the drop entirely from the code in the slide, and recommend adding it inside the nested let, to show that you can drop a variable in a nested scope. WDYT?

[njr0]

You mean remove all the drops? Or just the last one.

I think removing the last one would be fine. I don't see any advantage in removing the earlier ones, but I guess that would be OK too...

[djmitche]

The current example looks like

fn main() {
    let a = Droppable { name: "a" };
    {
        let b = Droppable { name: "b" };
        {
            let c = Droppable { name: "c" };
            let d = Droppable { name: "d" };
            println!("Exiting block B");
        }
        println!("Exiting block A");
    }
    drop(a);
    println!("Exiting main");
}

so there's only one drop. Or are we talking about different things?

[njr0]

You're right, of course. Apologies, I wasn't looking at the code when I replied. So yes, I agree.