let x = 42

let myAdd = fun x y -> x + y

let raisePowerTwo x = x ** 2.0

let مسعود = ""

let ``more? `` = true

let ``class`` = "style"

let test a b =
    let dif = b - a
    let mid = dif / 2
    mid + a

printfn "(test 5 11) = %i" (test 5 11)
printfn "(test 11 5) = %i" (test 11 5)

let halfWay a b =
let dif = b - a in
let mid = dif / 2 in
mid + a

#light "off"

 <td>{{ product.starRating }}</td>

import { Component, OnChanges, Input, Output, EventEmitter } from 'angular2/core';
 
@Component({
    selector: 'ai-star',
    templateUrl: 'app/shared/star.component.html',
    styleUrls: ['app/shared/star.component.css']
})
export class StarComponent implements OnChanges {
    @Input() rating: number;
    starWidth: number;
    @Output() ratingClicked: EventEmitter<string> = new EventEmitter<string>();
 
    ngOnChanges(): void {
        this.starWidth = this.rating * 86 / 5;
    }
 
    onClick() {
        this.ratingClicked.emit(`The rating ${this.rating} was clicked!`);
    }
}

<div class="crop"
     [style.width.px]="starWidth"
     [title]="rating"
     (click)='onClick()'>
    <div style="width: 86px">
        <span class="glyphicon glyphicon-star"></span>
        <span class="glyphicon glyphicon-star"></span>
        <span class="glyphicon glyphicon-star"></span>
        <span class="glyphicon glyphicon-star"></span>
        <span class="glyphicon glyphicon-star"></span>
    </div>
</div>

.crop {
    overflow: hidden;
}
 
div {
    cursor: pointer;
}

export class StarComponent implements OnChanges {
      @Input() rating: number;

 [rating]='product.starRating'

export class StarComponent implements OnChanges {
    @Input() rating: number;
    starWidth: number;
    @Output() ratingClicked: EventEmitter<string> = new EventEmitter<string>();

<div class="crop"
     [style.width.px]="starWidth"
     [title]="rating"
     (click)='onClick()'>

onClick() {
     this.ratingClicked.emit(`The rating ${this.rating} was clicked!`);
 }

 (ratingClicked)='onRatingClicked($event)'

onRatingClicked(message: string): void {
    this.pageTitle = 'Product List: ' + message;
}

<td>
    <ai-star [rating]='product.starRating'
             (ratingClicked)='onRatingClicked($event)'>
    </ai-star>
</td>

import { Component, OnInit } from 'angular2/core';
import { IProduct } from './product';
import { ProductFilterPipe } from './product-filter.pipe';
import { StarComponent } from '../shared/star.component';
 
@Component({
    selector: 'pm-products',
    templateUrl: 'app/products/product-list.component.html',
    styleUrls: ['app/products/product-list.component.css'],
    pipes: [ProductFilterPipe],
    directives: [StarComponent]
})

 <div id="my-element-id"></div>

 var result = $('#my-element-id');

 var result = document.getElementById('my-element-id');

  var result = document.querySelector('#my-element-id');

 result.id === 'my-element-id'; // returns true

<span class="some-class"></span>

 var result = $('.some-class');

  var result = document.getElementsByClassName('some-class');

 var result = document.querySelectorAll('.some-class');

 result[0].className === 'some-class'; // returns true

 <code>Console.WriteLine("Hello world!");</code>

 var result = $('code');

 var result = document.getElementsByTagName('code');

 var result = document.querySelectorAll('code');

 result[0].tagName === 'code'; // returns true

  <form>
     <label>Full Name
        <input name="full-name">
     </label>
     <label>Company
        <input name="company">
     </label>
  </form>

  var focusedInputs = $('INPUT:focus');

 var companyInput = document.querySelector('INPUT:focus');

  <div>
     <a href="https://www.dntips.ir">
        <span>Go to site</span>
     </a>
     <p>Some text</p>
     Some other text
  </div>

 var $result = $a.parent();

 var result = a.parentNode;

 var result = $('#myParent').children();

 var result = document.querySelectorAll('DIV > *');

  var result = document.querySelectorAll('DIV > P');

 var result = document.getElementById('myParent').childNodes;
var result = div.childNodes;

 var result =document.getElementById('myParent').children;

 var result =document.querySelectorAll('#myParent A');

  <ul role="menu">
     <li>choice 1</li>
     <li class="active">choice 2</li>
     <li>choice 3</li>
  </ul>

 var $result = $('UL LI').not('.active');

 var result = document.querySelectorAll('UL LI:not(.active)');

  <div id="link-container">
     <a href="https://github.com/VahidN">GitHub</a>
  </div>
  <ol>
     <li>one</li>
     <li>two</li>
  </ol>
  <span class="my-name">VahidN</span>

 var $result = $('#link-container, .my-name, OL');

 var result = document.querySelectorAll('#link-container, .my-name, OL');

 var result = document.querySelectorAll(
 'BUTTON[type="submit"], INPUT[type="submit"]'
);

window.$ = function(selector) {
     return document.querySelectorAll(selector);
};

  $('.some-class');
  $('#some-id');
  $('.some-parent > .some-child');
  $('UL LI:not(.active)');

services.AddDbContext<BloggingContext>(
   options => options.UseSqlServer(connectionString));

services.AddDbContextPool<BloggingContext>(
   options => options.UseSqlServer(connectionString));

public class BloggingContext : DbContext
{
   public BloggingContext(DbContextOptions<BloggingContext> options) : base(options){}

        public static void RunWithoutContextPooling()
        {
            Console.WriteLine("\nRun Without ContextPooling");
            var serviceProvider = new ServiceCollection()
                .AddEntityFrameworkSqlServer()
                .AddDbContext<BloggingContext>(
                    c => c.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Demo.ContextPooling;Trusted_Connection=True;ConnectRetryCount=0;"))
                .BuildServiceProvider();

            new RunTests().Start(serviceProvider);
        }

        public static void RunWithContextPooling()
        {
            Console.WriteLine("\nRun With ContextPooling");
            var serviceProvider = new ServiceCollection()
                .AddEntityFrameworkSqlServer()
                .AddDbContextPool<BloggingContext>(
                    c => c.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Demo.ContextPooling;Trusted_Connection=True;ConnectRetryCount=0;"),
                    poolSize: 16)
                .BuildServiceProvider();

            new RunTests().Start(serviceProvider);
        }

Run Without ContextPooling
[10:49:30.728] Context creations: 637 | Requests per second: 597
[10:49:31.746] Context creations: 1069 | Requests per second: 1050
[10:49:32.765] Context creations: 1088 | Requests per second: 1067
[10:49:33.784] Context creations: 1139 | Requests per second: 1119
[10:49:34.802] Context creations: 1138 | Requests per second: 1117
[10:49:35.831] Context creations: 1153 | Requests per second: 1120
[10:49:36.845] Context creations: 1126 | Requests per second: 1111
[10:49:37.873] Context creations: 1014 | Requests per second: 987
[10:49:38.898] Context creations: 1139 | Requests per second: 1111
[10:49:39.918] Context creations: 1086 | Requests per second: 1065

Total context creations: 10592
Requests per second:     1034

Run With ContextPooling
[10:49:40.982] Context creations: 32 | Requests per second: 1388
[10:49:41.991] Context creations: 0 | Requests per second: 1691
[10:49:43.014] Context creations: 0 | Requests per second: 1684
[10:49:44.031] Context creations: 0 | Requests per second: 1702
[10:49:45.049] Context creations: 0 | Requests per second: 1694
[10:49:46.067] Context creations: 0 | Requests per second: 1401
[10:49:47.075] Context creations: 0 | Requests per second: 1510
[10:49:48.107] Context creations: 0 | Requests per second: 1669
[10:49:49.127] Context creations: 0 | Requests per second: 1679
[10:49:50.147] Context creations: 0 | Requests per second: 1688

Total context creations: 32
Requests per second:     1610

public IEnumerable<Product> GetProducts()
{
    using (var stream = File.Read(Path.Combine(Environment.CurrentDirectory, "products.xml")))
    {
        var serializer = new XmlSerializer();
        return (IEnumerable<Product>)serializer.Deserialize(stream);
    }
}

public IEnumerable<Product> GetCachedProducts()
{
    var fullPath = Path.Combine(Environment.CurrentDirectory, "ProductCache.xml");
    if (!File.Exists(fullPath))
        return new Product[0];
         
    using (var stream = File.Read(fullPath))
    {
        var serializer = new XmlSerializer();
        return (IEnumerable<Product>)serializer.Deserialize(stream);
    }
}

IEnumerable<Product> GetProducts()

IEnumerable<Product> GetCachedProducts()

public class UserRepository : IUserRepository
{
    public IList<User> Search(string value)
    {
        try
        {
              return CreateConnectionAndACommandAndReturnAList("WHERE value=@value", Parameter.New("value", value));
        }
        catch (SqlException err)
        {
             var msg = String.Format("Ohh no!  Failed to search after users with '{0}' as search string", value);
             throw new DataSourceException(msg, err);
        }
    }
}

public void PrintName(string name)
{
     Console.WriteLine(name);
}

public void PrintName(string name)
{
    if (name == null) throw new ArgumentNullException("name");
     
     Console.WriteLine(name);
}

public void PrintName(string name)
{
    if (name == null) throw new ArgumentNullException("name");
    if (name.Length < 5 || name.Length > 10) throw new ArgumentOutOfRangeException("name", name, "Name must be between 5 or 10 characters long");
    if (name.Any(x => !char.IsAlphaNumeric(x)) throw new ArgumentOutOfRangeException("name", name, "May only contain alpha numerics");
     
     Console.WriteLine(name);
}

public User GetUser(int id)
{
}

var user = datasource.GetUser(userId);
if (user == null)
    throw new InvalidOperationException("Failed to find user: " + userId);
// actual logic here

public User GetUser(int id)
{
    if (id <= 0) throw new ArgumentOutOfRangeException("id", id, "Valid ids are from 1 and above. Do you have a parsing error somewhere?");
    
    var user = db.Execute<User>("WHERE Id = ?", id);
    if (user == null)
        throw new EntityNotFoundException("Failed to find user with id " + id);
        
    return user;
}

try
{
    FutileAttemptToResist();
}
catch (BorgException err)
{
     _myDearLog.Error("I'm in da cube! Ohh no!", err);
    throw err;
}

try
{
    GreaseTinMan();
}
catch (InvalidOperationException err)
{
    throw new TooScaredLion("The Lion was not in the m00d", err); //<---- استثناء اصلی بهتر است به استثناء جدید پاس داده شود
}

try
{
   socket.Connect("somethingawful.com", 80);
}
catch (SocketException err)
{
    throw new InvalidOperationException("Socket failed", err);  
}

void IncreaseStatusForUser(int userId, int newStatus)
{
    try
    {
         var user  = _repository.Get(userId);
         if (user == null)
             throw new UpdateException(string.Format("Failed to find user #{0} when trying to increase status to {1}", userId, newStatus));
    
         user.Status = newStatus;
         _repository.Save(user);
    }
   catch (DataSourceException err)
   {
       var errMsg = string.Format("Failed to find modify user #{0} when trying to increase status to {1}", userId, newStatus);
        throw new UpdateException(errMsg, err);
   }

public NewException()
public NewException(string description )
public NewException(string description, Exception inner)
protected or private NewException(SerializationInfo info, StreamingContext context)

“The given key was not present in the dictionary.”

“The key ‘abrakadabra’ was not present in the dictionary.”

public class SampleException : Exception
{
    public SampleException(string description)
        : base(description)
    {
        if (description == null) throw new ArgumentNullException("description");
    }
 
    public SampleException(string description, Exception inner)
        : base(description, inner)
    {
        if (description == null) throw new ArgumentNullException("description");
        if (inner == null) throw new ArgumentNullException("inner");
    }
 
    public SampleException(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }
}

public class HttpException : Exception
{
    System.Net.HttpStatusCode _statusCode;
     
    public HttpException(System.Net.HttpStatusCode statusCode, string description)
        : base(description)
    {
        if (description == null) throw new ArgumentNullException("description");
        _statusCode = statusCode;
    }
 
    public HttpException(System.Net.HttpStatusCode statusCode, string description, Exception inner)
        : base(description, inner)
    {
        if (description == null) throw new ArgumentNullException("description");
        if (inner == null) throw new ArgumentNullException("inner");
        _statusCode = statusCode;
    }
 
    public HttpException(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }
     
    public System.Net.HttpStatusCode StatusCode { get; private set; }
 
}

public override string Message
{
        get { return base.Message + "\r\nStatus code: " + StatusCode; }
}

public class HttpException : Exception
{
    // [...]
 
    public HttpException(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
        // this is new
        StatusCode = (HttpStatusCode) info.GetInt32("HttpStatusCode");
    }
 
    public HttpStatusCode StatusCode { get; private set; }
 
    public override string Message
    {
        get { return base.Message + "\r\nStatus code: " + StatusCode; }
    }
 
    // this is new
    public override void GetObjectData(SerializationInfo info, StreamingContext context)
    {
        base.GetObjectData(info, context);
        info.AddValue("HttpStatusCode", (int) StatusCode);
    }
}

throw new Exception("Unknown FaileType");
throw new Exception("Unecpected workingDirectory");

"Unecpected workingDirectory"

var scheduler = new StdSchedulerFactory().GetScheduler();

scheduler.Shutdown(true);

scheduler.DeleteJob(new JobKey("job1"));
// or
scheduler.UnscheduleJob(new TriggerKey("trigger1"));

scheduler.Standby();

scheduler.PauseJob(new JobKey("job1"));

scheduler.ResumeJob(new JobKey("job1"));

IJobDetail job = JobBuilder.Create<NewJob>()
                             .WithIdentity("job1")
                             .Build();

scheduler.AddJob(job, true);

ITrigger trigger = TriggerBuilder.Create()
                                 .WithIdentity("newTrigger")
                                 .StartNow()
                                 .ForJob("job1")
                                 .WithSimpleSchedule(x => x.WithIntervalInSeconds(5).WithRepeatCount(20))
                                 .Build();

scheduler.RescheduleJob(new TriggerKey("oldTrigger"), trigger);

ITrigger trigger = TriggerBuilder.Create()
                                 .WithIdentity("trigger1")
                                 .StartAt(startTime)
                                 .ForJob("job1")
                                 .WithSimpleSchedule(x => x.WithIntervalInSeconds(5).RepeatForever())
                                 .Build();

SchedulerMetaData metaData = scheduler.GetMetaData();

int numberOfJobsExecuted = metaData.NumberOfJobsExecuted;

SchedulerMetaData metaData = scheduler.GetMetaData();

DateTimeOffset? runningSince = metaData.RunningSince;

  defaultChecks() {
    const author = { firstName: "Vahid", lastName: "N" };
    console.log(author.lastname);
    author.lastName.trimStart();
    author.firstName.charCodeAt("1");
  }

  > npm install -g tslint typescript

{
    "compilerOptions": {
        "strictNullChecks": true
    }
}

  getSessionItem(key: string): any {
    const data = window.sessionStorage.getItem(key);
    return JSON.parse(data);
  }

[ts]
Argument of type 'string | null' is not assignable to parameter of type 'string'.
Type 'null' is not assignable to type 'string'.
const data: string | null

  getSessionItem(key: string): any {
    const data = window.sessionStorage.getItem(key);
    if (data) {
      return JSON.parse(data);
    } else {
      return null;
    }
  }

  noImplicitReturns(a: number) {
    if (a > 10) {
      return a;
    }
    // No return in this branch
  }

{
    "compilerOptions": {
        "noImplicitReturns": true
    }
}

 [ts] Not all code paths return a value.

{
    "compilerOptions": {
        "allowUnreachableCode": false
    }
}

    allowUnreachableCode() {
      if (false) {
        console.log("Unreachable code");
      }
      const a = 1;
      if (a > 0) {
        return 10; // reachable code
      }
      return 0;
      console.log("Unreachable code");
    }

  unusedLocals() {
    const a = "foo"; // Error: 'a' is declared but its value is never read
    return "bar";
  }

  unusedParameters(n: number) {
    n = 0; // Never read
  }

{
    "compilerOptions": {
        "noUnusedLocals": true,
        "noUnusedParameters": true
    }
}

[ts] 'a' is declared but its value is never read.
[ts] 'n' is declared but its value is never read.

  excessPropertyForObjectLiterals() {
    let x: { foo: number };
    x = { foo: 1, baz: 2 };  // Error, excess property 'baz'
    let y: { foo: number, bar?: number };
    y = { foo: 1, baz: 2 };  // Error, excess property 'baz'
  }

{
    "compilerOptions": {
        "suppressExcessPropertyErrors": false
    }
}

[ts]
Type '{ foo: number; baz: number; }' is not assignable to type '{ foo: number; }'.
Object literal may only specify known properties, and 'baz' does not exist in type '{ foo: number; }'.
(property) baz: number

  fallthroughCasesInSwitchStatement(a: number) {
    switch (a) {
      case 0:
        break;

      case 1:
        a += 1;

      case 2:
        a += 2;
        break;
    }
  }

{
    "compilerOptions": {
        "noFallthroughCasesInSwitch": true
    }
}

  indexingObjectsLackingIndexSignatures() {
    const x = { a: 0 };
    x["a"] = 1; // ok
    x["b"] = 1; // Error, type '{ a: number; }' has no index signature.
  }

{
    "compilerOptions": {
        "suppressImplicitAnyIndexErrors": false
    }
}

[ts] Element implicitly has an 'any' type because type '{ a: number; }' has no index signature.

{
    "compilerOptions": {
        "noImplicitAny": true
    }
}

  noImplicitAny(args) { // Error: Parameter 'args' implicitly has an 'any' type.
    console.log(args);
  }

  noImplicitAnyArgs(args: string[]) { // ok with the type information
    console.log(args);
  }

services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(connectionString));

public static IServiceCollection AddDbContext<TContext>(
    [NotNullAttribute] this IServiceCollection serviceCollection, 
    [CanBeNullAttribute] Action<DbContextOptionsBuilder> optionsAction = null, 
    ServiceLifetime contextLifetime = ServiceLifetime.Scoped, 
    ServiceLifetime optionsLifetime = ServiceLifetime.Scoped) where TContext : DbContext;

 An exception occurred while iterating over the results of a query for context type 'BlazorServer.DataAccess.ApplicationDbContext'.
System.InvalidOperationException: A second operation was started on this context before a previous operation completed.
This is usually caused by different threads concurrently using the same instance of DbContext.
For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

public void ConfigureServices(IServiceCollection services)
{
    var connectionString = Configuration.GetConnectionString("DefaultConnection");
    //services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(connectionString));
    services.AddDbContextFactory<ApplicationDbContext>(options => options.UseSqlServer(connectionString));

@inject IDbContextFactory<ApplicationDbContext> DbFactory

private async Task DeleteImageAsync()
{
    using var context = DbFactory.CreateDbContext();

    var image = await context.HotelRoomImages.FindAsync(1);

   // ...
}

@implements IDisposable
@inject IDbContextFactory<ApplicationDbContext> DbFactory


@code
{
   private ApplicationDbContext Context;

   protected override async Task OnInitializedAsync()
   {
       Context = DbFactory.CreateDbContext();
       await base.OnInitializedAsync();
   }

   private async Task DeleteImageAsync()
   {
       var image = await Context.HotelRoomImages.FindAsync(1);
       // ...
   }

   public void Dispose()
   {
     Context.Dispose();
   }
}

services.AddScoped<ApplicationDbContext>(serviceProvider =>
     serviceProvider.GetRequiredService<IDbContextFactory<ApplicationDbContext>>().CreateDbContext());

public interface IHotelRoomService : IDisposable
{
   // ...
}

public interface IHotelRoomImageService : IDisposable
{
   // ...
}

    public class HotelRoomService : IHotelRoomService
    {
        private bool _isDisposed;

        // ...

        public void Dispose()
        {
            Dispose(disposing: true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!_isDisposed)
            {
                try
                {
                    if (disposing)
                    {
                        _dbContext.Dispose();
                    }
                }
                finally
                {
                    _isDisposed = true;
                }
            }
        }
    }

@page "/hotel-room/create"
@page "/hotel-room/edit/{Id:int}"

@implements IDisposable
// ...


@code
{
    // ...

    public void Dispose()
    {
        HotelRoomImageService.Dispose();
        HotelRoomService.Dispose();
    }
}

@page "/hotel-room"

@implements IDisposable
// ...


@code
{
    // ...

    public void Dispose()
    {
        HotelRoomService.Dispose();
    }
}

System.ObjectDisposedException: Cannot access a disposed context instance.
A common cause of this error is disposing a context instance that was resolved from dependency injection and then
later trying to use the same context instance elsewhere in your application. This may occur if you are calling 'Dispose'
on the context instance, or wrapping it in a using statement. If you are using dependency injection, you should let the
dependency injection container take care of disposing context instances.
Object name: 'ApplicationDbContext'.

@code
{
   private IHotelRoomImageService HotelRoomImageService;

   protected override async Task OnInitializedAsync()
   {
       HotelRoomImageService =  new HotelRoomImageService(DbFactory.CreateDbContext(), mapper);
       await base.OnInitializedAsync();
   }

   private async Task DeleteImageAsync()
   {
       await HotelRoomImageService.DeleteAsync(1);
       // ...
   }

   public void Dispose()
   {
     HotelRoomImageService.Dispose();
   }
}

@page "/hotel-room"

@*@implements IDisposable*@
@*@inject IHotelRoomService HotelRoomService*@
@inherits OwningComponentBase<IHotelRoomService>

@code
{
   private IHotelRoomService HotelRoomService => Service;

@page "/preferences"
@using Microsoft.Extensions.DependencyInjection
@inherits OwningComponentBase


@code {
    private IHotelRoomService HotelRoomService { get; set; }
    private IHotelRoomImageService HotelRoomImageService { get; set; }

    protected override void OnInitialized()
    {
        HotelRoomService = ScopedServices.GetRequiredService<IHotelRoomService>();
        HotelRoomImageService = ScopedServices.GetRequiredService<IHotelRoomImageService>();
    }
}

services.AddDbContextFactory<ApplicationDbContext>(options => options.UseSqlServer(connectionString));
services.AddScoped<ApplicationDbContext>(serviceProvider =>
        serviceProvider.GetRequiredService<IDbContextFactory<ApplicationDbContext>>().CreateDbContext());

@inject IHotelRoomService HotelRoomService

@inherits OwningComponentBase<IHotelRoomService>