How to declare a constant Guid in C#?

Is it possible to declare a cons开发者_Python百科tant Guid in C#?

I understand that I can declare a static readonly Guid, but is there a syntax that allows me to write const Guid?

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No. The const modifier only applies to "primitive" types (bool, int, float, double, long, decimal, short, byte) and strings. Basically anything you can declare as a literal.

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Declare it as static readonly Guid rather than const Guid

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public static readonly Guid Users = new Guid("5C60F693-BEF5-E011-A485-80EE7300C695");

and that's that.

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While you can't seem to do that you can do that to be parsed whenever you need it:

const string _myGuidStr = "e6b86ea3-6479-48a2-b8d4-54bd6cbbdbc5";

But don't use the above guid as it belongs to me solely, I first generated it so I claim ownership on this particular guid above! But I'm generious - use this one instead (I don't like how it talks back to me but it's a nice guid overall when it keeps its mouth shut): 284c694d-d9cc-446b-9701-b391876c8394

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I am doing it like this:

public static class RecordTypeIds
{
    public const string USERS_TYPEID = "5C60F693-BEF5-E011-A485-80EE7300C695";
    public static Guid Users { get { return new Guid(EntityTypeIds.USERS_TYPEID); } }
}

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Depends on what you want a const for.

If you want to have a known GUID that you can reuse as needed, the above solution of storing the GUID as a string and parsing to GUID as needed works.

If you need a default parameter value, that won't work. The alternative is to use a nullable Guid and use null as your constant value.

public void Foo(string aParameter, Guid? anOptionalGuid = null)