From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Fri, 29 Apr 2022 21:17:10 +0000 (+0100)
Subject: ModifyingPieces: Provide on-your-own-head constructors, and doc
X-Git-Tag: otter-1.1.0~418
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=8e05679106697c01e32d54e04ee826f4fd5558b0;p=otter.git

ModifyingPieces: Provide on-your-own-head constructors, and doc

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/src/global.rs b/src/global.rs
index 487d79a7..2feb7cb2 100644
--- a/src/global.rs
+++ b/src/global.rs
@@ -89,6 +89,10 @@ deref_to_field!{IPiece, IPieceTraitObj, p}
 #[serde(transparent)]
 pub struct IPieces(ActualIPieces);
 pub type ActualIPieces = SecondarySlotMap<PieceId, IPiece>;
+
+/// Proof token that it is OK to modify the array
+///
+/// This exists to prevent bugs where we forget to save aux
 #[derive(Copy,Clone,Debug)]
 pub struct ModifyingPieces(());
 
@@ -282,6 +286,12 @@ impl Debug for Instance {
   }
 }
 
+impl ModifyingPieces {
+  pub fn allow_without_necessarily_saving() -> ModifyingPieces {
+    ModifyingPieces(())
+  }
+}
+
 // ---------- Main API for instance lifecycle ----------
 
 impl InstanceRef {
@@ -970,6 +980,12 @@ impl<'ig> InstanceGuard<'ig> {
     ModifyingPieces(())
   }
 
+  pub fn modify_pieces_not_necessarily_saving_aux(&mut self)
+                                                  -> ModifyingPieces {
+    self.save_game_later();
+    ModifyingPieces(())
+  }
+
   fn token_register<Id:AccessId>(
     &mut self,
     token: RawToken,