Why do I need it. does the qualifier use the extension method on the main page?

Question

I have the following line of code in some main page code behind, but it fails without this.Why is this?

Repeater rep = this.FindControlsByIdRegEx("maintTableRepeater")[0] as Repeater;

This is on the main page of the Load event, and the extension method is defined as:

        public static List<Control> FindControlsByIdRegEx(this Control control, string idPattern)

Answer 1

Extension methods must have an instance to hang.

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