From 447c62eae9e427a76b0ca35dabaf1eb1b2760485 Mon Sep 17 00:00:00 2001
From: Glen Whitney <glen@studioinfinity.org>
Date: Sun, 13 Apr 2025 02:00:20 -0700
Subject: [PATCH] fix: clear behaviors that depend on an object property

---
 src/core/Type.js                         | 5 +----
 src/core/TypeDispatcher.js               | 8 ++++++--
 src/core/__test__/TypeDispatcher.spec.js | 3 +++
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/core/Type.js b/src/core/Type.js
index 18530bc..7c728a2 100644
--- a/src/core/Type.js
+++ b/src/core/Type.js
@@ -1,10 +1,7 @@
-import {onType} from './helpers.js'
-
 export class Type {
    constructor(f, options = {}) {
       this.test = f
-      this.from = options.from ?? onType() // empty Implementations if no ...
-      // ... conversions specified
+      this.from = options.from ?? {patterns: []} // mock empty Implementations
    }
    toString() {
       return this.name || `[Type ${this.test}]`
diff --git a/src/core/TypeDispatcher.js b/src/core/TypeDispatcher.js
index 963f033..64757ce 100644
--- a/src/core/TypeDispatcher.js
+++ b/src/core/TypeDispatcher.js
@@ -32,7 +32,11 @@ export class TypeDispatcher {
       for (const key in spec) {
          let val = spec[key]
          if (val instanceof Type) {
-            // TODO: Need to wipe out any dependencies on types[key]!
+            // The design here is that we have set up the `types` property to
+            // be watched like any other, so the following assignment will
+            // cause any behaviors that depend on the type named `key` in the
+            // list of types to be cleared out automagically. Seems to work
+            // so far.
             this.types[key] = val
             val.name = key
             continue
@@ -353,7 +357,7 @@ const DependencyWatcher = (object, path, repo) => new Proxy(object, {
       // First see if this setting has any dependencies:
       const newPath = path.slice()
       newPath.push(prop)
-      const key = newPath.unshift()
+      const key = newPath.shift()
       const depSet = repo._dependencies[key]?.get(newPath)
       if (depSet?.size) {
          // It does. So if we are changing it, invalidate them:
diff --git a/src/core/__test__/TypeDispatcher.spec.js b/src/core/__test__/TypeDispatcher.spec.js
index 8c5bf81..81d91a3 100644
--- a/src/core/__test__/TypeDispatcher.spec.js
+++ b/src/core/__test__/TypeDispatcher.spec.js
@@ -41,6 +41,9 @@ describe('TypeDispatcher', () => {
          incremental.add.resolve([Undefined, NumberT]).returns,
          NumberT)
       assert.strictEqual(incremental.isnan(NaN), 1)
+      incremental.merge(booleans)
+      assert.strictEqual(incremental.boolean(undefined), false)
+      assert.strictEqual(incremental.isnan(NaN), true)
    })
    it('changes methods when their dependencies change', () => {
       const gnmath = new TypeDispatcher(generics, numbers)