Explicitly using an extension method

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Extension methods can also be used like ordinary static class methods. This way of calling an extension method is more verbose, but is necessary in some cases.

static class StringExtensions
    public static string Shorten(this string text, int length) 
        return text.Substring(0, length);


var newString = StringExtensions.Shorten("Hello World", 5);

When to call extension methods as static methods

There are still scenarios where you would need to use an extension method as a static method:

Using static

If a using static directive is used to bring static members of a static class into global scope, extension methods are skipped. Example:

using static OurNamespace.StringExtensions; // refers to class in previous example

// OK: extension method syntax still works.
"Hello World".Shorten(5);
// OK: static method syntax still works.
OurNamespace.StringExtensions.Shorten("Hello World", 5);
// Compile time error: extension methods can't be called as static without specifying class.
Shorten("Hello World", 5);

If you remove the this modifier from the first argument of the Shorten method, the last line will compile.

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