!21202 4.0beta2 changelog

Merge pull request !21202 from houhaoyu/master

zh-cn/release-notes/changelogs/v4.0-beta2/changelogs-arkui.md

+# arkui子系统ChangeLog
+
+
+## cl.arkui.1 编译拦截@Extend/@AnimatableExtend参数个数不符合预期
+
+@Extend/@AnimatableExtend装饰器参数有且仅能有一个。
+
+**变更影响**
+
+当@Extend/@AnimatableExtend装饰器参数有多个时，编译报错。
+
+**错误示例：**
+
+```ts
+// xxx.ets
+
+@Extend(Text, Button)  // 编译报错： @Extend should have one and only one parameter
+function fancy() {
+  .width(100)
+}
+
+@AnimatableExtend(Text, Polyline)  // 编译报错： @AnimatableExtend should have one and only one parameter
+function fancy2() {
+  .height(100)
+}
+
+@Entry
+@Component
+struct Example {
+  build() {
+    Column() {
+      Text('text')
+        .fancy()
+        .fancy2()
+    }
+  }
+}
+```
+
+**关键接口/组件变更**
+
+不涉及
+
+**适配指导**
+
+@Extend和AnimatableExtend装饰器仅能传一个参数。
+
+参考代码如下：
+```ts
+// xxx.ets
+
+@Extend(Text)
+function fancy() {
+  .width(100)
+}
+
+@AnimatableExtend(Text)
+function fancy2() {
+  .height(100)
+}
+
+@Entry
+@Component
+struct Example {
+  build() {
+    Column() {
+      Text('text')
+        .fancy()
+        .fancy2()
+    }
+  }
+}
+```
+
+## cl.arkui.2 编译拦截@Link/@ObjectLink成员变量未从父组件传值
+
+子组件的@Link/@ObjectLink成员变量需要从父组件传值。
+
+**变更影响**
+
+子组件的@Link/@ObjectLink当没有从父组件传值时，编译报错。
+
+**错误示例：**
+
+```ts
+// xxx.ets
+
+@Observed
+class Count {
+  message: string = 'count'
+}
+
+@Entry
+@Component
+struct Parent {
+  @State state1: string = 'state1';
+  @State state2: Count = new Count();
+  build() {
+    Column() {
+      Child()  // 编译报错：Property 'link' in the custom component 'Child' is missing (mandatory to specify).
+               // 编译报错：Property 'objectLink' in the custom component 'Child' is missing (mandatory to specify).
+    }
+  }
+}
+
+@Component
+struct Child {
+  @Link link: string;
+  @ObjectLink objectLink: Count;
+  build() {
+    Column() {
+      Text(this.link)
+        .fontSize(50)
+      Text(this.objectLink.message)
+        .fontSize(50)
+    }
+  }
+}
+```
+
+**关键接口/组件变更**
+
+不涉及
+
+**适配指导**
+
+子组件的@Link/@ObjectLink成员变量需要从父组件传值。
+
+参考代码如下：
+```ts
+// xxx.ets
+
+@Observed
+class Count {
+  message: string = 'count'
+}
+
+@Entry
+@Component
+struct Parent {
+  @State state1: string = 'state1';
+  @State state2: Count = new Count();
+  build() {
+    Column() {
+      Child({link: $state1, objectLink: this.state2})
+    }
+  }
+}
+
+@Component
+struct Child {
+  @Link link: string;
+  @ObjectLink objectLink: Count;
+  build() {
+    Column() {
+      Text(this.link)
+        .fontSize(50)
+      Text(this.objectLink.message)
+        .fontSize(50)
+    }
+  }
+}
+```