1# ArkUI Subsystem ChangeLog 2 3## cl.arkui.1 Restrictions on Data Type Declarations of State Variables 4 51. The data types of state variables decorated by state decorators must be explicitly declared. They cannot be declared as **any** or **Date**. 6 7 Example: 8 9 ```ts 10 // xxx.ets 11 @Entry 12 @Component 13 struct DatePickerExample { 14 // Incorrect: @State isLunar: any = false 15 @State isLunar: boolean = false 16 // Incorrect: @State selectedDate: Date = new Date('2021-08-08') 17 private selectedDate: Date = new Date('2021-08-08') 18 19 build() { 20 Column() { 21 Button('Switch Calendar') 22 .margin({ top: 30 }) 23 .onClick(() => { 24 this.isLunar = !this.isLunar 25 }) 26 DatePicker({ 27 start: new Date('1970-1-1'), 28 end: new Date('2100-1-1'), 29 selected: this.selectedDate 30 }) 31 .lunar(this.isLunar) 32 .onChange((value: DatePickerResult) => { 33 this.selectedDate.setFullYear(value.year, value.month, value.day) 34 console.info('select current date is: ' + JSON.stringify(value)) 35 }) 36 37 }.width('100%') 38 } 39 } 40 ``` 41 42  43 442. The data type declaration of the **@State**, **@Provide**, **@Link**, or **@Consume** decorated state variables can consist of only one of the primitive data types or reference data types. 45 46 The **Length**, **ResourceStr**, and **ResourceColor** types are combinations of primitive data types or reference data types. Therefore, they cannot be used by the aforementioned types of state variables. 47 For details about the definitions of **Length**, **ResourceStr**, and **ResourceColor**, see [Types](../../../application-dev/reference/arkui-ts/ts-types.md). 48 49 Example: 50 51 ```ts 52 // xxx.ets 53 @Entry 54 @Component 55 struct IndexPage { 56 // Incorrect: @State message: string | Resource = 'Hello World' 57 @State message: string = 'Hello World' 58 // Incorrect: @State message: ResourceStr = $r('app.string.hello') 59 @State resourceStr: Resource = $r('app.string.hello') 60 61 build() { 62 Row() { 63 Column() { 64 Text(`${this.message}`) 65 .fontSize(50) 66 .fontWeight(FontWeight.Bold) 67 } 68 .width('100%') 69 } 70 .height('100%') 71 } 72 } 73 ``` 74 75  76 77**Change Impacts** 78 791. If the data type of a state variable decorated by a state decorator is declared as **any**, a build error will occur. 80 ```ts 81 // ArkTS:ERROR Please define an explicit type, not any. 82 @State isLunar: any = false 83 ``` 842. If the data type of a state variable decorated by a state decorator is declared as **Date**, a build error will occur. 85 ```ts 86 // ArkTS:ERROR The @State property 'selectedDate' cannot be a 'Date' object. 87 @State selectedDate: Date = new Date('2021-08-08') 88 ``` 893. If the data type of a **@State**, **@Provide**, **@Link**, and or **@Consume** decorated state variable is Length, **ResourceStr**, or **ResourceColor**, a build error will occur. 90 ```ts 91 /* ArkTS:ERROR The state variable type here is 'ResourceStr', it contains both a simple type and an object type, 92 which are not allowed to be defined for state variable of a struct.*/ 93 @State message: ResourceStr = $r('app.string.hello') 94 ``` 95 96**Key API/Component Changes** 97 98N/A 99 100**Adaptation Guide** 101 1021. Explicitly declare the data type for state variables decorated by state decorators. 1032. If a state variable decorated by a state decorator uses the **Date** object, change it to a regular variable – a variable not decorated by any decorator. 1043. Adapt the **@State**, **@Provide**, **@Link**, and **@Consume** decorated variables based on the following code snippet so that they do not use the **Length(string|number|Resource)**, **ResourceStr(string|Resource)**, and **ResourceColor(string|number|Color|Resource)** types: 105 106 ```ts 107 // Incorrect: 108 @State message: ResourceStr = $r('app.string.hello') 109 // Corrected: 110 @State resourceStr: Resource = $r('app.string.hello') 111 ``` 112 113## cl.arkui.2 Initialization Rules and Restrictions of Custom Components' Member Variables 114 115Comply with the following rules when using constructors to initialize member variables: 116 117| **From the Variable in the Parent Component (Right) to the Variable in the Child Component (Below)**| **regular** | **@State** | **@Link** | **@Prop** | **@Provide** | **@Consume** | **@ObjectLink** | 118|---------------------------------|----------------------------|------------|-----------|-----------|--------------|--------------|------------------| 119| **regular** | Supported | Supported | Supported | Supported | Not supported | Not supported | Supported | 120| **@State** | Supported | Supported | Supported | Supported | Supported | Supported | Supported | 121| **@Link** | Not supported | Supported (1) | Supported (1) | Supported (1) | Supported (1) | Supported (1) | Supported (1) | 122| **@Prop** | Supported | Supported | Supported | Supported | Supported | Supported | Supported | 123| **@Provide** | Supported | Supported | Supported | Supported | Supported | Supported | Supported | 124| **@Consume** | Not supported | Not supported | Not supported | Not supported | Not supported | Not supported | Not supported | 125| **@ObjectLink** | Not supported | Not supported | Not supported | Not supported | Not supported | Not supported | Not supported | 126 127| **From the Variable in the Parent Component (Right) to the Variable in the Child Component (Below)**| **@StorageLink** | **@StorageProp** | **@LocalStorageLink** | **@LocalStorageProp** | 128|------------------|------------------|------------------|-----------------------|------------------------| 129| **regular** | Supported | Not supported | Not supported | Not supported | 130| **@State** | Supported | Supported | Supported | Supported | 131| **@Link** | Supported (1) | Supported (1) | Supported (1) | Supported (1) | 132| **@Prop** | Supported | Supported | Supported | Supported | 133| **@Provide** | Supported | Supported | Supported | Supported | 134| **@Consume** | Not supported | Not supported | Not supported | Not supported | 135| **@ObjectLink** | Not supported | Not supported | Not supported | Not supported | 136 137> **NOTE** 138> 139> **Supported (1)**: The dollar sign ($) must be used, for example, **this.$varA**. 140> 141> **regular**: refers to a regular variable that is not decorated by any decorator. 142 143**@StorageLink**, **@StorageProp**, **@LocalStorageLink**, and **@LocalStorageProp** variables cannot be initialized from the parent component. 144 145**Change Impacts** 146 1471. Variables decorated by **@LocalStorageLink** and **@LocalStorageProp** cannot be initialized from the parent component. 148 ```ts 149 @Entry 150 @Component 151 struct LocalStorageComponent { 152 build() { 153 Column() { 154 Child({ 155 /* ArkTS:ERROR Property 'simpleVarName' in the custom component 'Child' cannot 156 initialize here (forbidden to specify). */ 157 simpleVarName: 1, 158 /* ArkTS:ERROR Property 'objectName' in the custom component 'Child' cannot 159 initialize here (forbidden to specify). */ 160 objectName: new ClassA("x") 161 }) 162 } 163 } 164 } 165 @Component 166 struct Child { 167 @LocalStorageLink("storageSimpleProp") simpleVarName: number = 0; 168 @LocalStorageProp("storageObjectProp") objectName: ClassA = new ClassA("x"); 169 build() {} 170 } 171 ``` 1722. The **@ObjectLink** decorated variable cannot be directly initialized from a decorated variable in the parent component. The source of the parent component must be an array item or object attribute decorated by **@State**, **@Link**, **@Provide**, **@Consume**, or **@ObjectLink**. 173 ```ts 174 let NextID : number = 0; 175 176 @Observed class ClassA { 177 public id : number; 178 public c: number; 179 constructor(c: number) { 180 this.id = NextID++; 181 this.c = c; 182 } 183 } 184 185 @Component 186 struct Child { 187 @ObjectLink varA : ClassA; 188 build() { 189 Row() { 190 Text('ViewA-' + this.varA.id) 191 } 192 } 193 } 194 195 @Component 196 struct Parent { 197 @Link linkValue: ClassA 198 build() { 199 Column() { 200 /* ArkTS:ERROR The @Link property 'linkValue' cannot be assigned to 201 the @ObjectLink property 'varA'.*/ 202 Child({ varA: this.linkValue }) 203 } 204 } 205 } 206 ``` 207 208**Key API/Component Changes** 209 210N/A 211 212**Adaptation Guide** 2131. When building a child component, do not perform the build on the variables decorated by **@LocalStorageLink** and **@LocalStorageProp** in the child component. 214 215 To change these variables from the parent component, use the API provided by the **LocalStorage** (such as the **set** API) to assign values to them. 216 2172. For details about how to use **@ObjectLink**, see [@Observed and @ObjectLink](../../../application-dev/quick-start/arkts-observed-and-objectlink.md). 218
