extension-methods – Page 8

What is the best or most interesting use of Extension Methods you’ve seen? [closed]

February 21, 2023 by Tarik

This is one that’s been getting some play from me lately: public static IDisposable Tag(this HtmlHelper html, string tagName) { if (html == null) throw new ArgumentNullException(“html”); Action<string> a = tag => html.Write(String.Format(tag, tagName)); a(“<{0}>”); return new Memento(() => a(“</{0}>”)); } Used like: using (Html.Tag(“ul”)) { this.Model.ForEach(item => using(Html.Tag(“li”)) Html.Write(item)); using(Html.Tag(“li”)) Html.Write(“new”); } Memento is … Read more

How to compare nullable types?

February 15, 2023 by Tarik

C# supports “lifted” operators, so if the type (bool? in this case) is known at compile you should just be able to use: return x != y; If you need generics, then EqualityComparer<T>.Default is your friend: return !EqualityComparer<T>.Default.Equals(x,y); Note, however, that both of these approaches use the “null == null” approach (contrast to ANSI SQL). … Read more

Pass a lambda expression in place of IComparer or IEqualityComparer or any single-method interface?

February 10, 2023 by Tarik

I’m not much sure what useful it really is, as I think for most cases in the Base Library expecting an IComparer there’s an overload that expects a Comparison… but just for the record: in .Net 4.5 they’ve added a method to obtain an IComparer from a Comparison: Comparer.Create so you can pass your lambda … Read more

Can C# extension methods access private variables?

February 8, 2023 by Tarik

No. You can do the same in an extension method as in a “normal” static method in some utility class. So this extension method public static void SomeMethod(this string s) { // do something with ‘s’ } is equivalent to some static helper method like this (at least regarding what you can access): public static … Read more

Reflection to Identify Extension Methods

February 3, 2023 by Tarik

You have to look in all the assemblies where the extension method may be defined. Look for classes decorated with ExtensionAttribute, and then methods within that class which are also decorated with ExtensionAttribute. Then check the type of the first parameter to see if it matches the type you’re interested in. Here’s some complete code. … Read more

What Advantages of Extension Methods have you found? [closed]

January 29, 2023 by Tarik

The only advantage of extension methods is code readability. That’s it. Extension methods allow you to do this: foo.bar(); instead of this: Util.bar(foo); Now there are a lot of things in C# that are like this. In other words there are many features in C# that seem trivial and don’t have great benefit in and … Read more

Is it possible to create constructor-extension-method ? how?

January 27, 2023 by Tarik

No, but if you changed your AddRange signature to return the list instance, then you could at least do var list = new List<int>().AddRange(array, n); which imho is probably clearer than overloading the constructor anyway.

Swift extension example

January 25, 2023 by Tarik

Creating an extension Add a new swift file with File > New > File… > iOS > Source > Swift File. You can call it what you want. The general naming convention is to call it TypeName+NewFunctionality.swift. Example 1 – Double Double+Conversions.swift import Swift // or Foundation extension Double { func celsiusToFahrenheit() -> Double { … Read more

Why is the ‘this’ keyword required to call an extension method from within the extended class

January 23, 2023 by Tarik

A couple points: First off, the proposed feature (implicit “this.” on an extension method call) is unnecessary. Extension methods were necessary for LINQ query comprehensions to work the way we wanted; the receiver is always stated in the query so it is not necessary to support implicit this to make LINQ work. Second, the feature … Read more

How to extend C# built-in types, like String?

January 13, 2023 by Tarik

Since you cannot extend string.Trim(). You could make an Extension method as described here that trims and reduces whitespace. namespace CustomExtensions { //Extension methods must be defined in a static class public static class StringExtension { // This is the extension method. // The first parameter takes the “this” modifier // and specifies the type … Read more