How do I extend THE class, not the instance? [duplicate]

Question

Possible Duplicate:
Can you make an Extension Method Static/Shared?

Extension methods are great! Pardon my ignorance, but so far I've only found that you can extend a class to allow methods on its instances, but not the class itself.

Here's what I'm trying to do.
I have an enum like so:

enum ViewType
{
    Front_View,
    Back_View
}

And I already created an extension method ToDescription() to display a user-friendly textual representation of the view type, like so:

ViewType thisview = ViewType.Front_View;
string thisviewtext = thisview.ToDescription();  // translates to "Front View"

But later in the code, I want to parse from that translation back to the type, like this potential code if assuming I can extend the enum type itself:

// !!!NOT REAL CODE YET!!!
// translate to value ViewType.FrontView
ViewType newview = ViewType.ParseFromDescription("Front View");

How do I implement that ParseFromDescription(string) extension method (if possible)?

Answer 1

You can't do that. You could define a static helper class ViewTypeTools containing the method. Extension methods are basically the same thing, but a bit nicer to write.

Answer 2

You cannot make a static method callable as if it were contained in another static class. You cannot, for instance, create a String.IsNullOrBlank() function that checks the passed string for only whitespace in addition to being null or zero-length. You would have to have access to the String class code and add the method there.

To get the result you want, I would start with the string and implement an extension method ParseDescriptionToViewType() that will take the string as its "this" parameter and output the ViewType.