Implement appearing walls and popwalls

js/main.js

@@ -414,6 +414,18 @@ class Level {
         original_cell.is_dirty = true;
         goal_cell.is_dirty = true;
 
+        // Announce we're leaving, for the handful of tiles that care about it
+        original_cell.each(tile => {
+            if (tile === actor)
+                return;
+            if (actor.ignores(tile.type.name))
+                return;
+
+            if (tile.type.on_depart) {
+                tile.type.on_depart(tile, this, actor);
+            }
+        });
+
         // Step on all the tiles in the new cell
         if (actor === this.player) {
             this.hint_shown = null;

js/tiletypes.js

@@ -12,8 +12,14 @@ const TILE_TYPES = {
     },
     wall_appearing: {
         blocks: true,
+        on_bump(me, level, other) {
+            me.become('wall');
+        }
     },
     popwall: {
+        on_depart(me, level, other) {
+            me.become('wall');
+        }
     },
     thinwall_n: {
         thin_walls: new Set(['north']),