Enum.GetName() As Constant property

Question

I have been working in C# for about 8 months so forgive me if this is dumb...

I have an enum that I will need the string value several times in a class. So I want to use Enum.GetName() to set it to a string variable which is no problem. I just do it like so...

private string MyEnumString = Enum.GetName(typeof(MyEnum), MyEnum.Name);

And it works just fine.

But I tried to protect it a little better because this particular Enum is more important that all the others and it would not be good if I accidentally changed the string value somehow so I tried to make it const like this.

private const string MyEnumString = Enum.GetName(typeof(MyEnum), MyEnum.Name);

To my eyes this seems fine as it should all be known at compile time.

But Visual Studio 2013 Throws an error saying the "Cannot resolve symbol GetName". I know it works when it is not marked "const".

So this leads me with two questions about this? Why does it loose reference to the GetName enum? (After a bit of research I suspect it is something to do with GetName being a method and not a property of the Enum class but the error message just does not make sense to me)

And Finally is there a way to read the Name of MyEnum.Name to a const string other than what I am doing?

Answer 1

Just make it readonly:

private readonly string MyEnumString = Enum.GetName(typeof(MyEnum), MyEnum.Name);

Then it can't be changed afterwards.

You can't assign the result of calling a method to a constant; C# just doesn't allow it - the compiler would have to be calling that method at compile time, possibly before it was even compiled (and not only would it have to generate the IL, it would have to use the JIT compiler to compile that IL).

Enum.GetName(typeof(MyEnum), MyEnum.Name); is calling a method, so you can't assign the result to a constant.

[EDIT] As Jon Skeet says in a comment above, you can use nameof if using C#6 or later (i.e. VS2015 or later):

private const string MyEnumString = nameof(MyEnum.Name);

nameof works because here you are not calling an arbitrary method, but you are instead using a compiler feature to access the name of a type.