> The subscript operator can modify the map if the key if the is not present, so it is not constitute and thus formally not thread safe even if you are sure the key is always present.
Yeah, I know why it is unsafe in general, but I don't see why the C++ standard can't specify that operations that don't invalidate iterators are legal to perform in a concurrent manner provided they touch disjoint memory locations (for associative containers, subscripting is defined to be one such operator, as long as rehashing does not occur like in this case).
> At and find are always constitute so you can use those instead; no need to cache iterators.
Now that you mention it, I could have just called find every time. I guess I'm too used to it being O(n) for other collections and avoided it somewhat irrationally ;)
The wording could be changed. I guess it is just an issue of the committee only having ago items time; as there are alternatives here getting the correct wording right is not a priority so the fallback to const/non-cons thread safety guarantees is sufficient.
Yeah, I know why it is unsafe in general, but I don't see why the C++ standard can't specify that operations that don't invalidate iterators are legal to perform in a concurrent manner provided they touch disjoint memory locations (for associative containers, subscripting is defined to be one such operator, as long as rehashing does not occur like in this case).
> At and find are always constitute so you can use those instead; no need to cache iterators.
Now that you mention it, I could have just called find every time. I guess I'm too used to it being O(n) for other collections and avoided it somewhat irrationally ;)