Async / await

Before the C# 5.0, we had to write asynchronous methods with callbacks and be careful about error conditions. With "async" and "await" it's much more straight forward.

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace AsyncHttpClient
{
    /// <summary>
    /// Tiny example of using HttpClient.GetAsync() with Generics.
    /// Uses the REST API calls from the most excellent mysafeinfo.com for presidents and Beatles albums
    /// This prints:
    /// Requesting presidents
    /// Requesting Beatles albums
    /// ... waiting ...
    /// first president = number: '1','', party: '', term: ''
    /// first Beatles album = album name: 'Please Please Me (Mono)', date: '1963-03-22T00:00:00'
    /// </summary>
    public class President
    {
        public int president;
        public string name, party, term;
        public override string ToString() { return $"number: '{president}','{name}', party: '{party}', term: '{term}'"; }
    }
    public class BeatlesAlbum
    {
        public string album, date;
        public override string ToString() { return $"album name: '{album}', date: '{date}'"; }
    }

    class AsyncHttpClientExample
    {
            private static void Main()
        {
            string presidentsUrl = "https://mysafeinfo.com/api/data?list=presidents&format=json";
            string beatlesUrl = "https://mysafeinfo.com/api/data?list=beatlesalbums&format=json&select=ent,typ,rd&alias=ent=artist,typ=album,rd=date";
            var asyncHttpClientExample = new AsyncHttpClientExample();
            Console.Out.WriteLine("Requesting presidents");
            var presidents = asyncHttpClientExample.GetAsync<List<President>>(presidentsUrl);
            Console.Out.WriteLine("Requesting Beatles albums");
            var albums = asyncHttpClientExample.GetAsync<List<BeatlesAlbum>>(beatlesUrl);
            Console.Out.WriteLine("... waiting ...");
            Console.Out.WriteLine("first president = {0}", presidents.Result[0]);
            Console.Out.WriteLine("first Beatles album = {0}", albums.Result[0]);
        }
        private async Task<T> GetAsync<T>(string url)
        {
            HttpClient client = new HttpClient(new HttpClientHandler());
            HttpResponseMessage response = await client.GetAsync(url).ConfigureAwait(false);
            var jsonString = response.Content.ReadAsStringAsync().Result;
            T result = JsonConvert.DeserializeObject<T>(jsonString);

            return result;
        }
    }
}  

Caller Information

Although the stack trace object can be used to get similar information, C# 5.0 let's us get calling information for logging much more cheaply as shown in this example.

using System;
using System.Runtime.CompilerServices;

namespace Practice
{
    public class SeaSharp5
    {
        static void Main()
        {
            var seaSharp5 = new SeaSharp5();
            seaSharp5.MyCoolMethod();
            Console.Write("Press 'Enter' to exit.");Console.In.ReadLine();
        }
        public void MyCoolMethod()
        {
            //do some cool stuff here
            LogMessage("logging stuff here.");
        }

        public void LogMessage(string message,
            [CallerMemberName] string memberName = "",
            [CallerFilePath] string sourceFilePath = "",
            [CallerLineNumber] int sourceLineNumber = 0)
        {
            Console.WriteLine("My Message: " + message);
            Console.WriteLine("Calling method name: " + memberName);
            Console.WriteLine("Source file path: " + sourceFilePath);
            Console.WriteLine("Source line number of calling method: " + sourceLineNumber);
        }
    }
}

My Message: logging stuff here.
Calling method name: MyCoolMethod
Source file path: c:\Users\fincherm\Documents\Visual Studio 2015\Projects\Practice\Practice\SeaSharp5.cs
Source line number of calling method: 17
Press 'Enter' to exit.