I have a struct that looks like this:

pub struct Game {
    /// A HashSet with the players waiting to play as account strings.
    lobby: HashSet<String>,
    /// capacity determines  how many people a match contains.
    capacity: u8,
    /// A vector of ongoing matches.
    matches: Vec<Match>,
    /// HashSet indicating for each player which match they are in.
    players: HashMap<String, usize>,
}

I realised that this won’t work because if there are 3 matches (0, 1, 2) and I remove 1 because it ends, the players that used to point at 2 will be pointing outside the vector or to an incorrect match.

So I thought the obvious solution was to use a reference to the match: players: HashMap<String, &Match>. But this makes lifetimes very complicated.

What’s a good way to deal with a case like these where data are interrelated in the same struct?

  • expr@programming.dev
    0·
    7 months ago

    Could you not have a hashmap keyed on matches pointing to vectors of strings for the players in each match? Basically modeling the data how you want rather than relying on indexing.

    • modulus@lemmy.mlOP
      0·
      7 months ago

      Not sure I understand. What I’m trying to do is something like this:

      • Poll a stream which takes fedi events. Read player commands.
      • If an event comes from a known player, check which match they are into.
      • With that info, get their opponents/coplayers etc and perform the change of state in the game (send replies, next turn, etc).

      So what I have as a key is a player name (AP username) and from that I need to find which match they’re in.

      There’s nothing semantically useful about a match ID.