在 Swift 中当需要为属性添加相同的逻辑代码时使用属性包装器会大大减少工作量。属性包装器可以应用于结构体、枚举或者类。
如 Swift 官方文档中的示例，期望整型属性值始终小于 12，可以定义如下 TwelveOrLess 属性包装器：
// 定义 *TwelveOrLess* 属性包装器
@propertyWrapper
struct TwelveOrLess {
// 私有存储属性 number
private var number = 0
// 包装值
var wrappedValue: Int {
get { return number }
set { number = min(newValue, 12) }
}
}
// 使用 *TwelveOrLess* 来定义一个小矩形，长宽都小于等于一定值。
struct SmallRectangle {
@TwelveOrLess var height: Int
@TwelveOrLess var width: Int
}
var rectangle = SmallRectangle()
print(rectangle.height) // 打印 "0"
Manifest merger failed : Attribute application@name value=(com.example.moduledemo.MainApplication) from AndroidManifest.xml:7:9-40
is also present at [:live] AndroidManifest.xml:11:9-56 value=(com.example.live.LiveApplication).
Suggestion: add 'tools:replace="android:name"' to <application> element at AndroidManifest.xml:6:5-23:19 to override.
// Some samples to try
let strings = ["Hello", "98052", "101"];
// Validators to use
let validators: { [s: string]: StringValidator; } = {};
validators["ZIP code"] = new ZipCodeValidator();
validators["Letters only"] = new LettersOnlyValidator();
// Show whether each string passed each validator
for (let s of strings) {
for (let name in validators) {
let isMatch = validators[name].isAcceptable(s);
console.log(`'${ s }' ${ isMatch ? "matches" : "does not match" } '${ name }'.`);
}
}
// Some samples to try
let strings = ["Hello", "98052", "101"];
// Validators to use
let validators: { [s: string]: Validation.StringValidator; } = {};
validators["ZIP code"] = new Validation.ZipCodeValidator();
validators["Letters only"] = new Validation.LettersOnlyValidator();
// Show whether each string passed each validator
for (let s of strings) {
for (let name in validators) {
console.log(`"${ s }" - ${ validators[name].isAcceptable(s) ? "matches" : "does not match" } ${ name }`);
}
}
社区的小伙伴们，大家好啊，艰难的2020已经过去，随着2021的到来，在新的一年里希望大家都能够需求不变更、准点上下班、代码0 Bug。同时我们DoKit团队也给大家准备了一份特殊的“新年礼物”，没错它就是DoKit For Flutter，它来啦，它带着熟悉的配方来啦。接下来就让我们揭开它神秘的面纱吧。
滴滴做为国内最大的出行平台，早在两年前就有多个内部团队开始在Flutter领域进行尝试。但是在开发过程中，我们遇到了很多调试性问题，如日志、帧率、抓包等。为了解决这些开发测试过程中遇到的各类问题，我们DoKit团队联合滴滴代驾和货运团队，把平时工作过程中沉淀下来的效率工具进行业务剥离和脱敏，并最终打造出DoKit For Flutter，在服务内部业务的同时，也为社区贡献一份力量，这也是滴滴的开源精神。
介绍
DoKit For Flutter是一个DoKit针对Flutter环境的产研工具包，内部集成了各种丰富的小工具，UI、网络、内存、监控等等。DoKit始终站在用户的角度，为用户提供最便利的产研工具。
public static final int STATUS_NORMAL = 0;
public static final int STATUS_OPTIMISTIC = 1;
public static final int STATUS_OPEN = 2;
public static final int STATUS_CLOSE = 4;
//请问下面的console.log()输出什么？
function fn(a) {
//console.log(a);
var a = 123//变量赋值
//console.log(a);
function a() { }//函数声明
//console.log(a);
var b = function () { }//变量赋值（函数表达式）
//console.log(b);
function d() { }//函数声明
}
fn(1)//函数调用
The keys and the values stored with localStorage are always in the UTF-16 DOMString format, which uses two bytes per character. As with objects, integer keys are automatically converted to strings.
function sizeofUtf16Bytes(str) {
var total = 0,
charCode,
i,
len;
for (i = 0, len = str.length; i < len; i++) {
charCode = str.charCodeAt(i);
if (charCode <= 0xffff) {
total += 2;
} else {
total += 4;
}
}
return total;
}
继脸书（Facebook）把自己公司的名字改成了Meta之后，一贯对新概念保持低调态度的微软也终于放下了矜持，高调地加入了元宇宙的开拓大军。有意思的是，微软带给元宇宙的第一款产品叫做Mesh for Microsoft Teams。这是个什么样的产品呢？微软官方给出的说明是，这款产品要实现的主要是混合现实功能，把办公协作功能带入元宇宙。也就是说，现在人们在元宇宙也能用Excel制表、用PPT做幻灯片了！看着微软的这款新产品，打工人们不禁感叹：果然是“打工人，打工魂”，就算是躲进了元宇宙，终究还是逃不开打工的宿命啊！
尽管看起来有点不可思议：在类似元宇宙这样的一个虚拟世界，稀缺并非像真实世界那样，源自于物理规律的限制，而是来自于人们的建构，但现实确实是如此。事实上，现在人们所做的很多工作，就是试图在元宇宙当中构建起稀缺性。例如，现在的数字水印、数字权利管理（Digital Rights Management，简称DRM），以及非同质化通证（Non-Fungible Token，简称NFT）等重要技术，其实都是为了构建稀缺的技术。以前一段时间十分火爆的NFT为例，很多人都认为，这将是支撑未来元宇宙发展的一项关键技术。但是，NFT究竟有什么用呢？究其本质，就是它可以在元宇宙内创造出差异化、创造出稀缺。在元宇宙当中，人们完全可以对数码造物实现无限的复制，稀缺本来可以不存在。而借助于NFT技术，每一个物品都可以被打上独有的标签，或者赋予特殊的涵义，从而成为独一无二的东西。这样一来，稀缺就被制造了出来。
// 响应拦截
const { data } = useFetch(url, {
afterFetch(ctx) {
if (ctx.data.title === 'HxH')
ctx.data.title = 'Hunter x Hunter' // Modifies the resposne data
public static void testPrint() {
for (int i = 0; i < 5; i++) {
System.out.println("now " + i);
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try (Cost c = new Cost()) {
testPrint();
}
System.out.println("------over-------");
}
执行后输出如下:
now 0
now 1
now 2
now 3
now 4
cost: 55
------over-------
如果代码块抛异常，也会正常输出耗时么？
public static void testPrint() {
for (int i = 0; i < 5; i++) {
System.out.println("now " + i);
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
if (i == 3) {
throw new RuntimeException("some exception!");
}
}
}
再次输出如下，并没有问题
now 0
now 1
now 2
now 3
cost: 46
Exception in thread "main" java.lang.RuntimeException: some exception!
at com.git.hui.boot.order.Application.testPrint(Application.java:43)
at com.git.hui.boot.order.Application.main(Application.java:50)
/// link动态库
// link any inserted libraries
// do this after linking main executable so that any dylibs pulled in by inserted
// dylibs (e.g. libSystem) will not be in front of dylibs the program uses
if ( sInsertedDylibCount > 0 ) {
for(unsigned int i=0; i < sInsertedDylibCount; ++i) {
ImageLoader* image = sAllImages[i+1];
link(image, sEnv.DYLD_BIND_AT_LAUNCH, true, ImageLoader::RPathChain(NULL, NULL), -1);
image->setNeverUnloadRecursive();
}
if ( gLinkContext.allowInterposing ) {
// only INSERTED libraries can interpose
// register interposing info after all inserted libraries are bound so chaining works
for(unsigned int i=0; i < sInsertedDylibCount; ++i) {
ImageLoader* image = sAllImages[i+1];
image->registerInterposing(gLinkContext);
}
}
}
// Bind and notify for the inserted images now interposing has been registered
if ( sInsertedDylibCount > 0 ) {
for(unsigned int i=0; i < sInsertedDylibCount; ++i) {
ImageLoader* image = sAllImages[i+1];
image->recursiveBind(gLinkContext, sEnv.DYLD_BIND_AT_LAUNCH, true, nullptr);
}
}
代码省略......
/// 弱符号绑定
// <rdar://problem/12186933> do weak binding only after all inserted images linked
sMainExecutable->weakBind(gLinkContext);
代码省略......
/// 执行初始化方法
// run all initializers
initializeMainExecutable();
代码省略......
/// 寻找m目标可执行文件ru入口并执行
// main executable uses LC_UNIXTHREAD, dyld needs to let "start" in program set up for main()
result = (uintptr_t)sMainExecutable->getEntryFromLC_UNIXTHREAD();
A thread's autorelease pool is a stack of pointers. Each pointer is either an object to release, or POOL_BOUNDARY which is an autorelease pool boundary. A pool token is a pointer to the POOL_BOUNDARY for that pool. When the pool is popped, every object hotter than the sentinel is released. The stack is divided into a doubly-linked list of pages. Pages are added and deleted as necessary. Thread-local storage points to the hot page, where newly autoreleased objects are stored.
The Application Kit creates an autorelease pool on the main thread at the beginning of every cycle of the event loop, and drains it at the end, thereby releasing any autoreleased objects generated while processing an event. If you use the Application Kit, you therefore typically don’t have to create your own pools. If your application creates a lot of temporary autoreleased objects within the event loop, however, it may be beneficial to create “local” autorelease pools to help to minimize the peak memory footprint.
//AFNetworking 暴露给程序员自定义处理入口
if (self.authenticationChallengeHandler) {
id result = self.authenticationChallengeHandler(....);
... （解析处理结果）
}
...（证书认证处理代码）
//最后调用 completionHandler 继续执行操作
if (completionHandler) {
dyld: Library not loaded: /b/s/w/ir/k/homebrew/Cellar/libimobiledevice-flutter/HEAD-398c120_3/lib/libimobiledevice.6.dylib
Referenced from: /Users/hey/flutter/bin/cache/artifacts/libimobiledevice/idevice_id
Reason: image not found
删除&重新下载
rm -rf /Users/hey/flutter/bin/cache && flutter doctor -v
function double(x: number): number; // 输入是 number 类型，输出也是 number 类型
function double(x: string): string;
function double(x: number | string): number | string {
if (typeof x === 'number') {
return x * 2;
} else {
return x + ', ' + x;
}
}
