生成器函数内使用TS语言的限制

build() {
    let a: number = 1 // invalid: variable declaration not allowed
    console.log(`a: ${a}`) // invalid: console.log only allowed in first line of build
    Column() {
        Text('Hello ${this.myName.toUpperCase()}') // ok.
        ForEach(this.arr.reverse(), ..., ...) // invalid: Array.reverse modifies the @State array varible in place
    }
    buildSpecial()  // invalid: no function calls
    Text(this.calcTextValue()) // this function call is ok.
}