std::system::saves

Stability: Stable — save slots and their metadata.

std::system::saves names the save slots and reads and deletes them. Writing a save is Narrative::save(slot) (see std::narrative), because only a running game can be saved; loading one is nav::load(slot). The screenshot of a slot is the element ui::thumbnail(slot).

A save records the path the player took through the story; it stays loadable as long as the script still allows that path. See the Reference chapter Saves, Replay and Determinism for the model.

use std::system::saves;
use std::system::saves::SaveSlot;

Overview

Enum: SaveSlot

pub enum SaveSlot {
    /// Manual slot `k`, below `System::save_slots`.
    Manual(u32),
    /// The quick slot.
    Quick,
    /// Autosave slot `k`, below `System::auto_slots`.
    Auto(u32),
}

• A Manual(k) with k >= save_slots, or an Auto(k) with k >= auto_slots, is out of range. Using it is a runtime no-op: info returns None, and save does nothing.
• Autosave. At every choice step entry and on quit, the engine writes Auto(k), rotating through k in 0..auto_slots.

Struct: Timestamp

pub struct Timestamp {
    pub year: u16,
    pub month: u8,
    pub day: u8,
    pub hour: u8,
    pub minute: u8,
    pub second: u8,
}

A local date and time.

Struct: SaveInfo

pub struct SaveInfo {
    pub time: Timestamp,
    pub who: Option<Text>,
    pub text: Option<Text>,
}

What a slot shows: when it was saved and the line on screen at that time.

• time — when the save was written, in local time.
• who — the speaker of the line at save time, if any.
• text — the text of the line at save time, if a line was shown.

Struct: Divergence

#[builtin] pub struct Divergence;

Why a save no longer fits the program: the script changed so that the path recorded in the save is no longer a path of the story. Returned in the Err of nav::load.

Divergence::describe()

#[builtin] pub fn describe(&self) -> Text;

• Returns: Text — a description of where the save no longer fits the script, for the player.
• Kind: fn · Builtin: yes

Function: info(slot)

#[builtin] pub fn info(slot: SaveSlot) -> Option<SaveInfo>;

• slot SaveSlot — the slot.
• Returns: Option<SaveInfo> — the slot’s metadata, or None if the slot is empty or out of range.
• Kind: fn · Builtin: yes

info is a reactive source: a slot list re-renders when a save is written or deleted.

use std::system::saves;
use std::system::saves::SaveSlot;

fn slot_text(slot: SaveSlot) -> Text {
    match saves::info(slot) {
        Some(info) => match info.text {
            Some(text) => text,
            None => "",
        },
        None => "Empty",
    }
}

Function: delete(slot)

#[builtin] pub fn delete(slot: SaveSlot);

• slot SaveSlot — the slot to empty.
• Kind: fn · Builtin: yes

Empties the slot.

button!{on_click = || saves::delete(SaveSlot::Manual(0)), t!["Delete"]}

A full save and load page is in System Recipes.