On Tue, Dec 17, 2024 at 8:00 AM Neil Groves
It doesn't even need to be limited to containers. I think it generalizes to ranges. Isn't the free function along the lines of auto find_or(Rng&& rng, Key&& key, Default&& default) ? This works for all containers that allow the default to be something other than nullopt, which is very useful in many contexts. Where there are associative containers it can delegate to the optimal container implementation, but it can fall back to the general logic of std::ranges::find. A production version would, I assume, have the projection and other usual range idioms.
Working with ranges is an interesting idea, and comparisons to std::ranges::find might encounter obstacles. I presume that the OP was talking about returning an optional value given the key. This presumes an associative container. I am not too familiar with ranges, is there an "associative range" concept? I do like the default value idea though, thanks for that :) template< typename AssociativeContainer, typename Key, typename DefaultValue = std::nullopt > auto try_find( AssociativeContainer&& c, Key&& k, DefaultValue&& alternative = {} ) -> std::optional< typename AssociativeContainer::mapped_type >; Thanks