4 ms·
I understand why this works now, but stuff like this is why people avoid STL like the plague. Non-C++ languages would have just added a version of try_emplace w
by slaymaker1907 4y ago
I understand why this works now, but stuff like this is why people avoid STL like the plague. Non-C++ languages would have just added a version of try_emplace which accepts a lambda (or a function pointers plus a void pointer context).
Personally, I'd much rather see the try/catch version in my code base than the clever deferred evaluation version.
- thechao 4y agoMy gut feeling is that a lot of issues in this class are because the allocator for STL containers are built into the container, rather than passed-in. So, rather than: vector v; v.push_back(Bob{ }); It should be: vector v; v.push_back(BobAlloc, Bob{ }); But the ergonomics would be severely lacking.
- leni536 4y agoThat's a different issue. Tangentially related that Allocator::construct has the same slightly crippled interface, so both the allocator concept and the container interfaces would needed to be fixed for accepting a lambda. The stored allocator issue comes up when you need to store a bunch of vectors with the same stateful allocator, and you needlessly have to have a copy in each vector.
- Someone 4y agoI don’t think that would work. If every element of a vector can have its own allocator, and you later do v.erase(v.end() - 1); how would the vector know it has to call BobFree? The class _could_ store that with each element, but for small element sizes, that’s quite a bit of overhead.
- leni536 4y agoThat's quite correct. All of the functions in the standard library that have "emplace" in the name would be better off by accepting a lambda. Now they are stuck in having a "perfect forwarding" interface that is not perfect at all.