How do i serialize static class?

Question

I need to serialize static class with BinaryFormatter, here is the code:

    void Serialize()
    {
        IFormatter formatter = new BinaryFormatter();

        using (FileStream s = File.Create("ServerInfo.bin"))
            formatter.Serialize(s, Server); // ERROR: Error 44 'Server' is a 'type' but is used like a 'variable'

    }

How can i fix this?

Well what is `Server`? The error *clearly* states what the issue is. Do you have an instance of `Server`? No? Make one. — Arran, Nov 01 '13 at 15:53
Duplicate question: http://stackoverflow.com/q/1293496/1541819 — pescolino, Nov 01 '13 at 15:55
This topic was answered at http://stackoverflow.com/questions/1293496/serialize-a-static-class — Lucian0c, Nov 01 '13 at 15:56

score 12 · Accepted Answer · answered Nov 01 '13 at 15:55

12

You normally serialize instances. You can't have an instance of a static class, so it makes no sense to serialize it.

If you need to serialize the static state of a static class, then you should probably make it non-static to start with. If you really need to keep the static class static but serialize the static state, you could create a normal class with the same variables (but instance variables instead of static ones), and make methods in your static class to create an instance from the current static state, or replace the current static state based on an instance passed in. But fundamentally it's not terribly pleasant to do so...

answered Nov 01 '13 at 15:55

Jon Skeet

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7

Duplicate answer: http://stackoverflow.com/a/1293522/1541819 ;-) – pescolino Nov 01 '13 at 15:57
2

A fairly good way to emulate a static class is to implement it through a singleton. This keeps the class as an instance, but ensures only one copy of it. This way, you will be able to serialize it AND access it similarly to a static class (though through a static reference) – Serguei Fedorov Nov 01 '13 at 15:57

James · Answer 2 · 2013-11-01T16:10:22.057

2

The point of serialization is to serialize the state of an object and given static classes cannot be instantiated this suggests they aren't fit for serialization.

How can I fix this?

Consider creating a temporary class for serialization e.g. ServerState, transfer any state you want to store and use that instead

public static class Server
{
    public static ServerState CurrentState
    {
        return new ServerState
        {
            ...
        };
    }

    public static void LoadState(ServerState state)
    {
        ...
    }
}

...
IFormatter formatter = new BinaryFormatter();

using (FileStream s = File.Create("ServerInfo.bin"))
    formatter.Serialize(s, Server.CurrentState);

edited Nov 01 '13 at 16:10

answered Nov 01 '13 at 15:57

James

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A static class can certainly contain state - but it's all *static* state. – Jon Skeet Nov 01 '13 at 15:58
@JonSkeet yeah that's true, will remove that part from my answer. – James Nov 01 '13 at 15:59

score 2 · Answer 3 · answered Nov 01 '13 at 15:59

You can only serialize objects. Let's assume the Server class looks like this.

class Server
{
    public static string Name { get; set; }
    public static string IpAddresss { get; set; }
}

You cannot serialize this as there is no object to serialize. You could serialize the strings, but that's not what you want to do.

You can use the Singleton pattern to do this.

class Server
{
    private static Server _instance;
    public string Name { get; set; }
    public string IpAddress { get; set; }

    public static Server Instance 
    { 
        get { return _instance ?? ( _instance = new Server(); }
    }
}

There might be some issues with this, as I coded it in the browser.

score 1 · Answer 4 · answered Nov 01 '13 at 16:00

1

Most likely, what you want is to save the values of the variables. Just write a method in the class to do so. You can use any of the writer classes provided for streams and you can read them back using one of the reader classes.

answered Nov 01 '13 at 16:00

ThunderGr

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How do i serialize static class?

4 Answers4