I was previously using
let mut b = a.clone();
b.push(item);
But I found the following makes a significant performance difference in my use case
let mut b = Vec::with_capacity(a.len() + 1);
b.clone_from(&a);
b.push(item);
I was wondering if there is an already existing method to clone and append a single element?
Probably not, because doing that repeatedly is a very inefficient way to build a vector. You might be interested in im — data structures in Rust // Lib.rs
Or, if you're just looking for a one-liner, you could do
x.iter().chain([y]).cloned().collect()
That iterator will have an accurate size_hint, so won't need to reallocate the way that clone+push does.
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