#c-3.0

How to: C# Lambda expression, why should I use this? #development #it #dev

C# Lambda expression, why should I use this?

I have quickly read the Microsoft Lambda Expression documentation.

I see example that have help me to understand more like this one :

delegate int del(int i); del myDelegate = x => x * x; int j = myDelegate(5); //j = 25

But, I still do not understand why it’s so an innovation. It’s just a method that die when the “method variable” end, right? Why…

Fixed Populate XDocument from String #dev #it #asnwer

Populate XDocument from String

I’m working on a little something and I am trying to figure out whether I can load an XDocument from a string. XDocument.Load() seems to take the string passed to it as a path to a physical XML file.

I want to try and bypass the step of first having to create the physical XML file and jump straight to populating the XDocument.

Any ideas?

Answer: Populate XDocument…

How to: Why must a lambda expression be cast when supplied as a plain Delegate parameter

Why must a lambda expression be cast when supplied as a plain Delegate parameter

Take the method System.Windows.Forms.Control.Invoke(Delegate method)

Why does this give a compile time error:

string str = "woop"; Invoke(() => this.Text = str); // Error: Cannot convert lambda expression to type 'System.Delegate' // because it is not a delegate type

Yet this works fine:

string str = "woop";…

Fixed Getting all types that implement an interface #dev #it #asnwer

Getting all types that implement an interface

Using reflection, how can I get all types that implement an interface with C# 3.0/.NET 3.5 with the least code, and minimizing iterations?

This is what I want to re-write:

foreach (Type t in this.GetType().Assembly.GetTypes()) if (t is IMyInterface) ; //do stuff

Answer: Getting all types that implement an interface

This worked for me (if you wish…

How to: How to get index using LINQ?

How to get index using LINQ?

Given a datasource like that:

var c = new Car[] { new Car{ Color="Blue", Price=28000}, new Car{ Color="Red", Price=54000}, new Car{ Color="Pink", Price=9999}, // .. };

How can I find the index of the first car satisfying a certain condition with LINQ?

EDIT:

I could think of something like this but it looks horrible:

int firstItem = someItems.Select((item, index) =>…

Fixed What's the hardest or most misunderstood aspect of LINQ? #dev #it #asnwer

What’s the hardest or most misunderstood aspect of LINQ?

Background: Over the next month, I’ll be giving three talks about or at least including LINQ in the context of C#. I’d like to know which topics are worth giving a fair amount of attention to, based on what people may find hard to understand, or what they may have a mistaken impression of. I won’t be specifically talking about LINQ to SQLo…

Fixed Distinct() with lambda? #dev #it #asnwer

Distinct() with lambda?

Right, so I have an enumerable and wish to get distinct values from it.

Using System.Linq, there’s of course an extension method called Distinct. In the simple case, it can be used with no parameters, like:

var distinctValues = myStringList.Distinct();

Well and good, but if I have an enumerable of objects for which I need to specify equality, the only available overload…

How to: Help a C# developer understand: What is a monad?

Help a C# developer understand: What is a monad?

There is a lot of talk about monads these days. I have read a few articles / blog posts, but I can’t go far enough with their examples to fully grasp the concept. The reason is that monads are a functional language concept, and thus the examples are in languages I haven’t worked with (since I haven’t used a functional language in depth). I can’t…