在下面的示例中,在函数Test()中,第一行编译成功,而第二行没有编译,尽管我有一个KeyValuePair的Deconstruct扩展方法。为什么会这样呢?
public static class Tests {
class Foo { }
class Bar { }
public static void Test() {
// This works:
Bar[] works = new List<ValueTuple<Foo, Bar>>()
.Select(((Foo foo, B
我相信这是显而易见的,但我不明白为什么现在不能工作……
我在Vue项目中有一个文件,它以两种不同的格式导出键码,一种用于常量(allCodes),另一种用于Vue (keyCodes):
export default {
allCodes,
keyCodes
};
当我尝试像这样使用解构来导入其中的一个时,我得到了一个错误:
import { allCodes } from '@/helpers/keycodes';
21:17-25 "export 'allCodes' was not found in '@/helpers/keyco
我正在寻找一种在解构对象时操作数据的智能方法。看一下下面的代码: let employee = {
name: 'John Doe',
birthday: '1980/01/01', // yyyy/MM/dd format
department: 'R&D'
}
const { name, birthday, department } = employee
console.log(`${name} is working under ${department} and their birthday is on $
function useState(initVal){
const state = initVal
const setState = (newVal) => {
state = newVal
}
}
const [state,setState] = useState(0)
console.log(state)
TypeError: useState is not a function or its return value is not iterable
at /home/runner/ViciousSqueakyProfessionals/index.
我想知道是否有可能在swift中实现,获取属性值并将其赋给与Js同名的变量 import Foundation
struct Car: Codable {
var name, color, licensePlate: String
}
struct User: Codable {
var name, surname: String
var car: [Car]
var number: Int = 0
}
let DB5 = Car(name: "Aston Martin DB5", color: "gray", licen
假设我有一个枚举池,我想要按属性分组:
cars = Car.all.group_by(&:color)
然后我想像这样遍历这些cars:
cars.inject([]) do |stack, (color, cars)|
stack << cars.each do |car|
...
end
end
块变量扩展的术语是什么(在圆括号之间)?
我在React Native中得到以下代码的错误: Invalid attempt to destructure non-iterable instance. In order to be iterable, non-array object must have a [symbol.iterator]() method counter-context.js import React, {useState, createContext} from 'react'
export const CounterContext = createContext();
export co
我有Person类
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public void Deconstruct(out int id) { id = Id; }
}
当我试图用以下代码解构它时:
var (id) = new Person();
编译器说:
无法推断隐式解构变量'id‘的类型。
当有多个参数时,编译器不会这么说。如下所示:
public void Deconstruct(out int id, out string n
我在尝试创建节点ID时遇到了一个问题。这个问题在我的gatsby-node.js文件中...该错误来自exports.sourceNodes,其中的错误为: createNodeId is not a function
TypeError: createNodeId is not a function
gatsby-node.js:32
/home/jorge/Desktop/gatsby_practice/jorge-blog/gatsby-node.js:32:15
Array.forEach
gatsby-node.js:27 Object.exports.sourceNode