I'm (and millions other people) are using macOS with a classic scroll wheel mouse perfectly fine. Are you sure there is not something messing with the trackpad at the same time ? (this looking erratically random?)

There is no trackpad connected, just the Magic Mouse that was charging. Maybe it is because of some setting stored inside the mouse (it's a Razer mini). I think it has something to do with the scroll speed that macOS cannot deal with.

As I said, I'm sure I can fix it, but the point is that it works just fine as is on Windows and Linux.

Logitech mice are appreciated on Macs because they generally make drivers to deal with macOS idiosyncracies. A generic mouse will probably work OK but will be painful to deal with. macOS expects scrolling to work with inertia because of their focus on the trackpad or touch surface for the Magic Mouse.

Having used both extensively, it's not all bad, and I think they actually got some things right, but the problem is they make it hard for 3rd parties to make hardware because the APIs are lacking or inaccessible. For example, they just enabled linear mouse movement without relying on 3rd-party software; Windows has had that option since basically forever.

Apple does have some good things, but you can't argue with the fact that they make it very hard to integrate 3rd-party solutions (display are the same, notably for brightness control, etc).

TLDR: DBtune identified and tuned key server parameters that seem to have had a large impact, including random_page_cost and max_wal_size

Zed uses clangd, I don't think clangd support only 90% of C++ (and I don't think it avoid hard work).

export template extern still exists.

TIL that std::visit supports multiple variants. How new is that ?

Always did, as far as I know. Never knew why...

Obviously you can delete than iterate. He means delete while iterating.

Ah, ok. But then: you kinda can't do that at all. You certainly shouldn't.

For unordered_map (and every hash table in the known universe) erasing anything invalidates all iterators, so you can't iterate while erasing. For std::map, you can if you're very, very careful (erasing invalidates the iterator you're currently on, but if you cache the next iterator, THEN erase the current one, it'll probably work, but be very fiddly). Most languages forbid this entirely: e.g. Rust's ownership model doesn't allow it, Python throws an exception, etc. It's just a very bad idea in general.

Iterator-based std::unordered_map::erase and std::map::erase return a new iterator, one past the range erased, specifically so that you can erase while iterating. Along these untested lines:

    for(decltype(cont)::const_iterator it=cont.begin();it!=cont.end();++it){
        if(Keep(it.first)){
            ++it;
        }else{
            it=cont.erase(it);
        }
    }

There's an argument to be made that maybe you should do something else, but if you want to do the above, you can!

Huh, TIL! I didn't realize that, I just always avoid this pattern because it's such a common source of bugs (and if I really need to, I just use the erase_if).

EDIT: just saw your example and checked cppreference, it says the return value "Iterator following the last removed element" for std::unordered_map. So i think you need to add an `it--` after your erase, otherwise it will "skip over" the next element. Right?

Also just read this little nugget on cppreference for unordered_map::erase:

> Removes specified elements from the container.The order of the remaining elements is preserved. (This makes it possible to erase individual elements while iterating through the container.)

This seems like a crazy guarantee to put in the standard, it must really limit the kinds of hash tables you can make that matches the unordered_map interface.

The return value refers to the same element that you'd reach by skipping over the elemnent(s) rather than deleting them. So if doing 1 elemnt at a time, you can ++it (and now it is the next element), or you can it=erase(it) (and now the current item is gone, and it is the next element).

(In the map/unordered_map/set/etc. case, you can get away with storing std::advance(it) and then erasing, but when forward-iterating vectors the iterator invalidation rules are quite different and the API is designed to cover this.)

> This seems like a crazy guarantee to put in the standard

It’s a great and useful guarantee.

> it must really limit the kinds of hash tables you can make that matches the unordered_map interface.

Many libraries treat containers as “abstract” with many possible implementations. STL explicitly does not. It’s a specific data structure from a computer science class.

What is the use case for that? Seems more like a footgun, at least for a generic container interface.

Surely you must be kidding? Inserting/removing in a container while iterating through it is one of the all time greatest and most iconic bugs. People do it because they want to do it.

In reality, very few real-life containers can support this pattern, which is why this is a headline case for Rust, because it statically prevents this bug.

But yes, for removal the correct thing is always to use `std::erase_if` (C++) or `retain()` (Rust). For insertions, the only real solution is to build up a separate collection while iterating and then merging it into the original container when done. Yucky, but won't crash.

All containers can (at least theoretically) support modifying the container while iterating. You just have to adjust the iterator to take account for the changed container. C++'s std::map::erase(iterator) returns a new iterator for exactly this purpose - the iterator pointing to the next element before the operation but one that is still valid after the operation. Unfortunately you can't use it with range-based for loops even though they still use iterators under the hood but c'est la vie.

Sure they can, but if you define an interface that allows this, every container type implementing it must support it, and it is probably gonna be rather slow operation for the effort. That's why the question is not "can you do this?" but "why would you want to do this?". I can't think of a good reason for generic containers, if you need something like that, it should be a purpose-built data structure that efficiently supports it.

The STL containers are full of "features" that containers in other languages just do not support, yet it's worse to use in my opinion.

It happens surprisingly often.

Examples of better design than abseil in a pure C++20 implementation

Most of CSS is indeed statically typed (property have statically typed valid values). It's not true anymore when you introduce custom properties and IACVT though.

Custom properties can also be typed https://developer.mozilla.org/en-US/docs/Web/CSS/@property