Archive for the ‘linq’ Tag

C# 3.0 – Linq queries and Implicit Types

Finally played a bit with Linq today. About time, a lot of people will say, and rightly so. Just dipping my toes right now: wrote a short console application to list all current processes running more than 5 threads (no real use – just playing).

The whole thing was pleasantly intuitive, and the script is shown in its entirety below:

 
using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Diagnostics; 
using System.IO;  

namespace MyFirstLinq 
{ 
    class Program 
    { 
        static void Main(string[] args) 
        { 
            Process[] processes = Process.GetProcesses();  

            var query = 
                from process in processes 
                where 
                    process.Threads.Count > 5 
                orderby process.Threads.Count descending 
                select new { process.ProcessName, process.Threads.Count };  

            foreach (var result in query) 
                Console.WriteLine("{0} ({1} threads)", 
                    result.ProcessName, 
                    result.Count);  

            Console.ReadKey(); 
        } 
    } 
} 

While writing this, I also had a look at the implicit type declaration (the var keyword in the code) – already ran into this while talking to Marlon the C# Monk a few days ago (thanks again for taking the time to explain stuff – helps loads!). This form of declaration looks extremely handy – you get the benefits of strongly typed return values, without the hassle of having to write several small classes that are unlikely to be used anywhere else, ever (Annoying, but has my vote for the lesser of two evils – using object arrays for return values is messy).

According to MSDN, implicit types can only be used within the method scope. This makes sense, since if you’re going to start passing them around, you will probably need to declare a proper class for their values anyway.

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