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public IEnumerable<User> SelectUsers() { // Execute an SQL query on a database. using (IDataReader reader = this.Database.ExecuteReader(CommandType.Text, "SELECT Id, Name FROM Users")) { while (reader.Read()) { int id = reader.GetInt32(0...

You can extend the functionality of existing yield methods by passing in one or more values or elements that could define a terminating condition within the function by calling a yield break to stop the inner loop from executing. public static IEnumerable<int> CountUntilAny(int start, HashSet...

using System.Collections.Generic; using System.Collections.ObjectModel; using System.ComponentModel.Composition; namespace Demo { [Export(typeof(IUserProvider))] public sealed class UserProvider : IUserProvider { public ReadOnlyCollection<User> GetAllUsers() ...

using System; using System.ComponentModel.Composition; namespace Demo { public sealed class UserWriter { [Import(typeof(IUserProvider))] private IUserProvider userProvider; public void PrintAllUsers() { foreach (User user in this.user...

See the other (Basic) examples above. using System.ComponentModel.Composition; using System.ComponentModel.Composition.Hosting; namespace Demo { public static class Program { public static void Main() { using (var catalog = new ApplicationCatalog()) ...

Just like other methods, extension methods can use generics. For example: static class Extensions { public static bool HasMoreThanThreeElements<T>(this IEnumerable<T> enumerable) { return enumerable.Take(4).Count() > 3; } } and calling it would be like: ...

class Program { static void Main(string[] args) { // Run 2 Tasks. var task1 = Task.Run(() => PerformAction(1))); var task2 = Task.Run(() => PerformAction(2))); // Wait (i.e. block this thread) until both Tasks are complete. Task.WaitA...

1 - Create an empty folder, it will contain the files created in the next steps. 2 - Create a file named project.json with the following content (adjust the port number and rootDirectory as appropriate): { "dependencies": { "Microsoft.AspNet.Server.Kestrel": "1.0.0...

Typically lambdas are used for defining simple functions (generally in the context of a linq expression): var incremented = myEnumerable.Select(x => x + 1); Here the return is implicit. However, it is also possible to pass actions as lambdas: myObservable.Do(x => Console.WriteLine(x)); ...

An iterator method is not executed until the return value is enumerated. It's therefore advantageous to assert preconditions outside of the iterator. public static IEnumerable<int> Count(int start, int count) { // The exception will throw when the method is called, not when the result i...

Use parentheses around the expression to the left of the => operator to indicate multiple parameters. delegate int ModifyInt(int input1, int input2); ModifyInt multiplyTwoInts = (x,y) => x * y; Similarly, an empty set of parentheses indicates that the function does not accept parameters. ...

Given following nullable int int? i = 10; In case default value is needed, you can assign one using null coalescing operator, GetValueOrDefault method or check if nullable int HasValue before assignment. int j = i ?? 0; int j = i.GetValueOrDefault(0); int j = i.HasValue ? i.Value : 0; The ...

Imports System Module Program Public Sub Main() Console.WriteLine("Hello World") End Sub End Module Live Demo in Action at .NET Fiddle Introduction to Visual Basic .NET

The left-hand operand must be nullable, while the right-hand operand may or may not be. The result will be typed accordingly. Non-nullable int? a = null; int b = 3; var output = a ?? b; var type = output.GetType(); Console.WriteLine($"Output Type :{type}"); Console.WriteLine($&q...

open System [<EntryPoint>] let main argv = printfn "Hello World" 0 Live Demo in Action at .NET Fiddle Introduction to F#

Explicit interface implementation is necessary when you implement multiple interfaces who define a common method, but different implementations are required depending on which interface is being used to call the method (note that you don't need explicit implementations if multiple interfaces share t...

// Connect to a target server using your ConnectionMultiplexer instance IServer server = conn.GetServer("localhost", 6379); // Write out each key in the server foreach(var key in server.Keys()) { Console.WriteLine(key); }

// Connect to a target server using your ConnectionMultiplexer instance IServer server = conn.GetServer("localhost", 6379); var seq = server.Keys(); IScanningCursor scanningCursor = (IScanningCursor)seq; // Use the cursor in some way...

It is possible to use multiple nested using statements without added multiple levels of nested braces. For example: using (var input = File.OpenRead("input.txt")) { using (var output = File.OpenWrite("output.txt")) { input.CopyTo(output); } // output is ...

public class SingletonClass { public static SingletonClass Instance { get; } = new SingletonClass(); private SingletonClass() { // Put custom constructor code here } } Because the constructor is private, no new instances of SingletonClass can be made by consum...