Re: ordered string-list considered harmful, was Re: [PATCH v3] Allow aliases that include other aliases
From: Jonathan Nieder <hidden>
Date: 2018-09-07 06:32:46
Jeff King wrote:
I don't see any point in generating a sorted list and _then_ making an auxiliary hashmap. My idea was that if you're using a sorted string-list for lookup, then you can replace the whole thing with a hash (inserting as you go, rather than sorting at the end).
What if I'm sorting a string list in preparation for emitting a sorted list, and I *also* want to perform lookups in that same list? In other words: [...]
I think Stefan pointed out a "case 4" in the other part of the thread: ones where we really care not just about fast lookup, but actual iteration order.
I had assumed that that was the whole point of this data structure. Anything else that is using it for lookups should indeed use a hash map instead, and I can take my share of blame for missing this kind of thing in review. [...]
I think I like the hashmap way, if the conversion isn't too painful.
If we don't have any callers that actually need the sort-and-lookup thing, then yay, let's get rid of it. But I don't actually think of this as the hashmap way. It's the get-rid-of-the-unneeded-feature way. In other words, *regardless* of what else we should do, we should update any callers that want a hashmap to use a hashmap. Please go ahead, even if it doesn't let us simplify the string list API at all. Thanks, Jonathan