A Quicksilver Chanukah, Day 3: Gestalt

Often your application might want to store gamestate or configurations, but the web has no filesystem access. Additionally, you don’t want to just dump files in the user’s home directory; each desktop operating system has a different preferred location for storing application-specific data, and often different locations for different kinds of data.

Introducing gestalt, a library that bundles up your data and stores it away so you don’t have to.

A sample to save some game state:

use gestalt::{Location, save, load};
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct Player {
    name: String,
    score: u32
}

let player1 = Player { name: "Bob".to_string(), score: 21 };
save(Location::Cache, "mygame", "player1", &player1).expect("Could not save Player 1");

let player2 = Player { name: "Alice".to_string(), score: 200 };
save(Location::Cache, "mygame", "player2", &player2).expect("Could not save Player 2");

// Now reload.
let player1 = load::<Player>(Location::Cache, "mygame", "player1").expect("Could not load Player 1");
let player2 = load::<Player>(Location::Cache, "mygame", "player2").expect("Could not load Player 2");

Getsalt creates a Key/Value store, backed by the filesystem on desktop and the web storage API. The key is formed by Location, which determines the kind of data (Location::Cache, Location::Data, and Location::Config), the application name, and a string which identifies the name of the data chunk. The value is anything that implements Serialize from serde.

Cache is for data that can be cleared between runs of your application; Data is for blobs like save states, and Config is for application settings. gestalt uses dirs to ensure that it saves your data in the right place for each, regardless of your user’s operating system.

That’s Day 3 done: gestalt is pretty small! Tomorrow’s library, blinds, starts to get quite a bit bigger.