Can I add extension methods to an existing static class?

Question

I\'m a fan of extension methods in C#, but haven\'t had any success adding an extension method to a static class, such as Console.

For example, if I want to add an e

Answer 1

The following was rejected as an edit to tvanfosson's answer. I was asked to contribute it as my own answer. I used his suggestion and finished the implementation of a ConfigurationManager wrapper. In principle I simply filled out the ... in tvanfosson's answer.

No. Extension methods require an instance of an object. You can however, write a static wrapper around the ConfigurationManager interface. If you implement the wrapper, you don't need an extension method since you can just add the method directly.

public static class ConfigurationManagerWrapper
{
    public static NameValueCollection AppSettings
    {
        get { return ConfigurationManager.AppSettings; }
    }

    public static ConnectionStringSettingsCollection ConnectionStrings
    {
        get { return ConfigurationManager.ConnectionStrings; }
    }

    public static object GetSection(string sectionName)
    {
        return ConfigurationManager.GetSection(sectionName);
    }

    public static Configuration OpenExeConfiguration(string exePath)
    {
        return ConfigurationManager.OpenExeConfiguration(exePath);
    }

    public static Configuration OpenMachineConfiguration()
    {
        return ConfigurationManager.OpenMachineConfiguration();
    }

    public static Configuration OpenMappedExeConfiguration(ExeConfigurationFileMap fileMap, ConfigurationUserLevel userLevel)
    {
        return ConfigurationManager.OpenMappedExeConfiguration(fileMap, userLevel);
    }

    public static Configuration OpenMappedMachineConfiguration(ConfigurationFileMap fileMap)
    {
        return ConfigurationManager.OpenMappedMachineConfiguration(fileMap);
    }

    public static void RefreshSection(string sectionName)
    {
        ConfigurationManager.RefreshSection(sectionName);
    }
}