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Royi Namir
Royi Namir

Reputation: 148744

Why static fields initialization occurs before the static constructor?

The following code: 

static void Main(string[] args)
{
    Console.WriteLine("0");
    string h = Foo.X;
    Console.WriteLine("2");
}

public static class Foo
{
    public static string X = ((Func<string, string>)delegate(string g)
    {
        Console.WriteLine(g);
        return (g);
    })("_aaa");

    static Foo()
    {
        Console.WriteLine("ctor");
    }
}

Will print:

0
_aaa
ctor
2

I know about the beforefieldinit behavior (with/without static constructor etc.).

The thing which I don't understand is why the ctor (in the output) is after _aaa?

It doesn't make any sense, what if I want to initialize variables in the constructor?

Question

Why does the initialization of X is before the ctor?

Upvotes: 12

Views: 4498

Answers (1)

Jo&#227;o Angelo
Jo&#227;o Angelo

Reputation: 57728

The reason ctor is after the field initializers is because that's the way it is specified. From the C# specification (emphasis is mine):

10.5.5.1 Static field initialization The static field variable initializers of a class correspond to a sequence of assignments that are executed in the textual order in which they appear in the class declaration. If a static constructor (§10.12) exists in the class, execution of the static field initializers occurs immediately prior to executing that static constructor. Otherwise, the static field initializers are executed at an implementation-dependent time prior to the first use of a static field of that class

If you want to have total control of your initialization order, move it all inside the constructor.

Upvotes: 18

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