Can C# extension methods access private variables?

Question

Is it possible to access an object's private variables using an extension method?

Answer 1

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 void SomeStringMethod(string s)
{
 // do something with 's'
}

(Of course you could use some reflection in either method to access private members. But I guess that's not the point of this question.)

Answer 2

No, unless you give some kind of access to them through public properties or a proxy pattern.

Answer 3

No:

public class Foo
{
    private string bar;
}

public static class FooExtensions
{
    public static void Test(this Foo foo)
    {
        // Compile error here: Foo.bar is inaccessible due to its protection level  
        var bar = foo.bar;
    }
}

Answer 4

An extension method is essentially a static method so all you have access to are the public members of the instance on which the extension method is invoked on

Answer 5

Look at this example

http://www.codeproject.com/Articles/80343/Accessing-private-members.aspx