What is the equivalent of a 'friend' keyword in C Sharp?

Question

What is the equivalent of a 'friend' keyword in C Sharp?

How do I use the 'internal' keyword?

I have read that 'internal' keyword is a replacement for 'friend' in C#.

I am using a DLL in my C# project that I have the source code for and yet I do not want to modify the existing code. I have inherited the class and I can use my inherited class any way I want. The problem is that most of the code in the parent class has protected methods. Will using a friend somehow make it possible to access or call these protected methods?

Answer 1

1. You can use the keyword access modifier internal to declare a type or type member as accessible to code in the same assembly only.

2. You can use the InternalsVisibleToAttribute class defined in System.Rutime.CompilerServices to declare a type as accessible to code in the same assembly or a specified assembly only.

You use the first as you use any other access modifier such as private. To wit:

internal class MyClass {
    ...
}

You use the second as follows:

[assembly:InternalsVisibleTo("MyFriendAssembly", PublicKey="...")]
internal class MyVisibleClass {
    ...
}

Both of these can rightly be considered the equivalent of friend in C#.

Methods that are protected are already available to derived classes.

Answer 2

No, "internal" is not the same as "friend" (at least the C++ 'friend')

friend specifies that this class is only accessible by ONE, particular class.
internal specifies that this class is accessible by ANY class in the assembly.

Answer 3

1) Internal is the C# equivelant of the VB.NET 'friend' keyword, as you have guessed (as opposed to a replacement)

2) Usage is as follows

internal void Function() {}
internal Class Classname() {}
internal int myInt;
internal int MyProperty { get; set; }

3) It, basically, is an access modifier that stipulates that the accessibility of the class / function / vairiable / property marked as internal is as if it were public to the Assembly it is compiled in, and private to any other assemblies

Answer 4

Your subclass will be able to access the protected members of the class you inherit.

Are you looking to give access to these protected members to another class?

Answer 5

Internal is the equivalent of friend. A protected method is only available within the same class or from an inheritor. If you're trying to expose protected methods from an inheritor, you can wrap them in public methods.