How can I run a static constructor?

Question

I'd like to execute the static constructor of a class (i.e. I want to "load" the class) without creating an instance. How do I do that?

Bonus question: Are there any differences between .NET 4 and older versions?

Edit:

• The class is not static.
• I want to run it before creating instances because it takes a while to run, and I'd like to avoid this delay at first access.
• The static ctor initializes private static readonly fields thus cannot be run in a method instead.

Answer 1

Static classes do not have constructors. What do you need to "load" ?

Answer 2

The static constructor runs automatically the first time you access the class. There is no need (or capability) to 'run' it yourself.

Answer 3

There is no need to do this, the whole point of a static constructor is that it runs once when the class is first initialised at first access. If you want to run something on demand, then consider adding your initialisation code into a public method that is called by the constructor. You can then call this method whenever you like. But I'm not sure why you would want to do this?

Answer 4

As others have said, static constructors run automatically. If you need to be explicit, maybe you should refactor it into a static method which you can run explicitly?

Explicitly calling a static method would also, of course, ensure that the static constructor had been executed.

edit

Static constructors are run when any static members are referenced. You could simply create a dummy method called initialize which did nothing but ensure that the framework calls the static constructor.

Answer 5

Just reference one of your static fields. This will force your static initialization code to run. For example:

public class MyClass {
  private static readonly someStaticField;

  static MyClass() { someStaticField = ... }

  // any no-op method call accepting your object will do fine
  public static void TouchMe() { Equals(someStaticField, null); }
}

Usage:

// initialize statics
MyClass.TouchMe();

Answer 6

The cctor (static constructor) will be called whenever one of the following occurs;

1. You create an instance of the class
2. Any static member is accessed
3. Any time before that if BeforeFieldInit is set

If you want to explicitly invoke the cctor, assuming you have other static members, just invoke/access them.

If you are not doing anything very interesting in your cctor, the compiler may decide to mark it BeforeFieldInit, which will allow the CLR the option to execute the cctor early. This is explained in more detail here: http://blogs.msdn.com/davidnotario/archive/2005/02/08/369593.aspx

Answer 7

The other answers are excellent, but if you need to force a class constructor to run without having a reference to the type (ie. reflection), you can use:

Type type = ...;
System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(type.TypeHandle);