alt Hacker NewsC++ operator [] is poorly designed: index, and index+assignment should be two different operators, and indexing alone should never insert new entries into the map.
Languages like D [0] or Rust [1] get this right.
[0]: https://dlang.org/spec/operatoroverloading.html#index_assign... [1]: https://doc.rust-lang.org/std/ops/trait.IndexMut.html
Replies
Tempest1981 • yesterday at 11:40 PM
iirc, there are 5 ways to put something into a std::map
operator[], insert(), emplace(), try_emplace(), insert_or_assign()
Lots of people are surprised that insert() can fail. And even more surprised that a RHS [] inserts a default value. I'm not a fan of APIs that surprise.
You could (and I would) make the opposite statement: upsert should be the default operator and if you want lookup only or insert only you call different operators.
I find it annoying that I often have to reach to defaultdict in Python to get this behavior.