Merge pull request #663 from NullVoxPopuli/cell-update

feat(cell): add update method to Cell class

Author: NullVoxPopuli

ember-resources/src/util/cell.ts

@@ -12,6 +12,10 @@ class Cell<Value = unknown> {
     }
   }
 
+  /**
+   * Toggles the value of `current` only if
+   * `current` is a boolean -- errors otherwise
+   */
   toggle = () => {
     assert(
       `toggle can only be used when 'current' is a boolean type`,
@@ -20,6 +24,21 @@ class Cell<Value = unknown> {
 
     (this.current as boolean) = !this.current;
   };
+
+  /**
+   * Updates the value of `current`
+   * by calling a function that recieves the previous value.
+   */
+  update = (updater: (prevValue: Value) => Value) => {
+    this.current = updater(this.current);
+  };
+
+  /**
+   * Updates the value of `current`
+   */
+  set = (nextValue: Value) => {
+    this.current = nextValue;
+  };
 }
 
 /**
@@ -58,7 +77,7 @@ class Cell<Value = unknown> {
  */
 export function cell<Value = unknown>(initialValue?: Value): Cell<Value> {
   if (initialValue !== undefined) {
-    return new Cell(initialValue);
+    return new Cell(initialValue as Value);
   }
 
   return new Cell();

pnpm-lock.yaml

@@ -31,4 +31,24 @@ module('Utils | cell | rendering', function (hooks) {
 
     assert.dom().hasText('1');
   });
+
+  test('it can be updated via update / set', async function (assert) {
+    let state = cell(0);
+
+    await render(<template>{{state.current}}</template>);
+
+    assert.dom().hasText('0');
+
+    state.set(10);
+    await settled();
+
+    assert.dom().hasText('10');
+
+    state.update(prev => {
+      return prev / 5
+    });
+    await settled();
+    assert.dom().hasText('2');
+
+  })
 });