It would be really simple to optimize this by simply adding 1 to the pointer if str.starts_with? '+'. I think this optimization is so easy it might be a good idea to do it now to avoid the string copy and extra garbage.

yeah, it's done in String#lchop.

@Sija What do you mean? lchop creates a new string. We should just ignore the first char if it's +, like what @RX14 says.

My bad indeed. str = str[1..-1] if str.starts_with?('+')?

Wouldn't be better to implement it directly in String#lchop instead?

It's not possible. All strings have 8 leading bytes: four bytes for the type_id, and four bytes for the string's size. So a substring must have this info too.

In any case, I consider this an optimization. We can merge this now and optimize it later.

Yes, it's an optimization. However, we'll probably forget if this is merged as-is. This is a very simple optimization:

unsafe_str = str.to_unsafe
unsafe_str += 1 if str.starts_with?('+')

then use unsafe_str. If you don't want to implement it, that's fine, it's just simple enough that now is as good a time as any to do this.

I'd like to merge it as-is and leave this perf optimization to the most interested parties like yourself. Thank you.

I general I hate it that we need such unsafe code. We should maybe work with slices in most cases unless we can prove a big performance loss.