[BUGFIX beta] Use a symbol to detect if an object is a stream.

packages/ember-glimmer/tests/integration/components/curly-components-test.js

@@ -917,4 +917,43 @@ moduleFor('Components test: curly components', class extends RenderingTest {
     this.assertElement(this.firstChild.childNodes[2], { tagName: 'b', content: 'bold' });
   }
 
+  ['@test can use isStream property without conflict (#13271)']() {
+    let component;
+    let FooBarComponent = Component.extend({
+      isStream: true,
+
+      init() {
+        this._super(...arguments);
+        component = this;
+      }
+    });
+
+    this.registerComponent('foo-bar', {
+      ComponentClass: FooBarComponent,
+
+      template: strip`
+        {{#if isStream}}
+          true
+        {{else}}
+          false
+        {{/if}}
+      `
+    });
+
+    this.render('{{foo-bar}}');
+
+    this.assertComponentElement(this.firstChild, { content: 'true' });
+
+    this.runTask(() => this.rerender());
+
+    this.assertComponentElement(this.firstChild, { content: 'true' });
+
+    this.runTask(() => set(component, 'isStream', false));
+
+    this.assertComponentElement(this.firstChild, { content: 'false' });
+
+    this.runTask(() => set(component, 'isStream', true));
+
+    this.assertComponentElement(this.firstChild, { content: 'true' });
+  }
 });

packages/ember-metal/lib/streams/stream.js

@@ -8,6 +8,10 @@ import Subscriber from 'ember-metal/streams/subscriber';
 import Dependency from 'ember-metal/streams/dependency';
 import { GUID_KEY } from 'ember-metal/utils';
 import require from 'require';
+import symbol from 'ember-metal/symbol';
+
+export const IS_STREAM = symbol('IS_STREAM');
+
 /**
   @module ember-metal
 */
@@ -26,9 +30,8 @@ var KeyStream;
 var ProxyMixin;
 
 BasicStream.prototype = {
-  isStream: true,
-
   _init(label) {
+    this[IS_STREAM] = true;
     this.label = makeLabel(label);
     this.isActive = false;
     this.isDirty = true;

packages/ember-metal/lib/streams/utils.js

@@ -1,5 +1,6 @@
 import { assert } from 'ember-metal/debug';
 import BasicStream, { Stream } from './stream';
+import { IS_STREAM } from 'ember-metal/streams/stream';
 
 /*
  Check whether an object is a stream or not.
@@ -11,7 +12,7 @@ import BasicStream, { Stream } from './stream';
  @return {Boolean} `true` if the object is a stream, `false` otherwise.
 */
 export function isStream(object) {
-  return object && object.isStream;
+  return object && object[IS_STREAM];
 }
 
 /*
@@ -27,7 +28,7 @@ export function isStream(object) {
                            is provided.
  */
 export function subscribe(object, callback, context) {
-  if (object && object.isStream) {
+  if (object && object[IS_STREAM]) {
     return object.subscribe(callback, context);
   }
 }
@@ -44,7 +45,7 @@ export function subscribe(object, callback, context) {
  @param {Object} [context] Object originally passed to `subscribe()`.
  */
 export function unsubscribe(object, callback, context) {
-  if (object && object.isStream) {
+  if (object && object[IS_STREAM]) {
     object.unsubscribe(callback, context);
   }
 }
@@ -60,7 +61,7 @@ export function unsubscribe(object, callback, context) {
  @return The stream's current value, or the non-stream object itself.
  */
 export function read(object) {
-  if (object && object.isStream) {
+  if (object && object[IS_STREAM]) {
     return object.value();
   } else {
     return object;
@@ -343,7 +344,7 @@ export function chain(value, fn, label) {
 }
 
 export function setValue(object, value) {
-  if (object && object.isStream) {
+  if (object && object[IS_STREAM]) {
     object.setValue(value);
   }
 }

packages/ember-metal/tests/streams/concat_test.js

@@ -1,7 +1,8 @@
 import { Stream } from 'ember-metal/streams/stream';
 import {
   concat,
-  read
+  read,
+  isStream
 } from 'ember-metal/streams/utils';
 
 
@@ -28,7 +29,7 @@ QUnit.test('returns a stream if a stream is in the array', function(assert) {
   });
   let result = concat(['foo', stream, 'baz'], ' ');
 
-  assert.ok(result.isStream, 'a stream is returned');
+  assert.ok(isStream(result), 'a stream is returned');
   assert.equal(read(result), 'foo bar baz');
 });