Differences between extension methods in C#3 & 4

Posted by Buh Buh on Stack Overflow See other posts from Stack Overflow or by Buh Buh
Published on 2011-01-04T11:47:31Z Indexed on 2011/01/04 11:53 UTC
Read the original article Hit count: 186

Filed under:

c#

|

extension-methods

|

versions

I think I remember reading a long time ago that in C#3 extension methods could only be applied to primitive types and interfaces; and that in C#4 they could be used to extend any type. This doesn't seam to match up with what I am seeing now and I am finding it difficult to find this documented.

Is there any truth to this or did my memory make it all up?

What are the rules relating to which types can be extended?

Are there any differences between C# 3 and 4?

© Stack Overflow or respective owner

Related posts about c#

.NET WebRequest.PreAuthenticate not quite what it sounds like

as seen on West-Wind - Search for 'West-Wind'
I’ve run into the problem a few times now: How to pre-authenticate .NET WebRequest calls doing an HTTP call to the server – essentially send authentication credentials on the very first request instead of waiting for a server challenge first? At first glance this sound like it should be easy:… >>> More
HttpWebRequest and Ignoring SSL Certificate Errors

as seen on West-Wind - Search for 'West-Wind'
Man I can't believe this. I'm still mucking around with OFX servers and it drives me absolutely crazy how some these servers are just so unbelievably misconfigured. I've recently hit three different 3 major brokerages which fail HTTP validation with bad or corrupt certificates at least according to… >>> More
The dynamic Type in C# Simplifies COM Member Access from Visual FoxPro

as seen on West-Wind - Search for 'West-Wind'
I’ve written quite a bit about Visual FoxPro interoperating with .NET in the past both for ASP.NET interacting with Visual FoxPro COM objects as well as Visual FoxPro calling into .NET code via COM Interop. COM Interop with Visual FoxPro has a number of problems but one of them at least got a lot… >>> More
Dynamic Type to do away with Reflection

as seen on West-Wind - Search for 'West-Wind'
The dynamic type in C# 4.0 is a welcome addition to the language. One thing I’ve been doing a lot with it is to remove explicit Reflection code that’s often necessary when you ‘dynamically’ need to walk and object hierarchy. In the past I’ve had a number of ReflectionUtils that used string based expressions… >>> More
Finding a Relative Path in .NET

as seen on West-Wind - Search for 'West-Wind'
Here’s a nice and simple path utility that I’ve needed in a number of applications: I need to find a relative path based on a base path. So if I’m working in a folder called c:\temp\templates\ and I want to find a relative path for c:\temp\templates\subdir\test.txt I want to receive back subdir\test… >>> More

Related posts about extension-methods

Collect all extension methods to generic class in another generic class

as seen on Stack Overflow - Search for 'Stack Overflow'
I'd like to create a lot of extension methods for some generic class, e.g. for public class SimpleLinkedList<T> where T:IComparable And I've started creating methods like this: public static class LinkedListExtensions { public static T[] ToArray<T>(this SimpleLinkedList<T>… >>> More
Lambdas within Extension methods: Possible memory leak?

as seen on Stack Overflow - Search for 'Stack Overflow'
I just gave an answer to a quite simple question by using an extension method. But after writing it down i remembered that you can't unsubscribe a lambda from an event handler. So far no big problem. But how does all this behave within an extension method?? Below is my code snipped again. So can… >>> More
Having trouble with extension methods for byte arrays

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm working with a device that sends back an image, and when I request an image, there is some undocumented information that comes before the image data. I was only able to realize this by looking through the binary data and identifying the image header information inside. I've been able to make… >>> More
Extension Methods in Dot Net 2.0

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
Not that anyone would still need this, but in case you have a situation where the code MUST be .NET 2.0 compliant and you want to use a cool feature like Extension methods, there is a way. I saw this article when looking for ways to create extension methods in C++, C# and VB: http://msdn.microsoft… >>> More
Prefer extension methods for encapsulation and reusability?

as seen on Stack Overflow - Search for 'Stack Overflow'
edit4: wikified, since this seems to have morphed more into a discussion than a specific question. In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs… >>> More