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Anonymous Method Serialization

, 12 Feb 2009 CPOL
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Anonymous method serialization


Anonymous methods cannot be serialized in C# (unless they do not reference any stack variables). The most simple solution would be to add the [Serializable] attribute to the anonymous class generated for the method, but since this is (as far as I know) not possible yet, we have to use this "hack".

This is an updated version of Jeremy Thomas' version that can be found here, with the improvement that this also supports nested delegates, and any delegate.

Please note that this code is not very well tested.  Also note that anything you reference inside the anonymous method also gets serialized, including this. This means that, if you serialize a delegate referencing this and then deserialize it again and run it, then this will refer to a new copy of the object.

Using the Code 

formater.Serialize(stream, new SerializeDelegate(myDelegate));


public class SerializeDelegate : ISerializable
    internal SerializeDelegate(Delegate delegate_)
        this.delegate_ = delegate_;

    internal SerializeDelegate(SerializationInfo info, StreamingContext context)
        Type delType = (Type)info.GetValue("delegateType", typeof(Type));

        //If it's a "simple" delegate we just read it straight off
        if (info.GetBoolean("isSerializable"))
            this.delegate_ = (Delegate)info.GetValue("delegate", delType);

        //otherwise, we need to read its anonymous class
            MethodInfo method = (MethodInfo)info.GetValue("method", typeof(MethodInfo));

            AnonymousClassWrapper w = 
			("class", typeof(AnonymousClassWrapper));

            delegate_ = Delegate.CreateDelegate(delType, w.obj, method);

    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
        info.AddValue("delegateType", delegate_.GetType());

        //If it's an "simple" delegate we can serialize it directly
        if ((delegate_.Target == null ||
                .GetCustomAttributes(typeof(SerializableAttribute), false).Length > 0) &&
            delegate_ != null)
            info.AddValue("isSerializable", true);
            info.AddValue("delegate", delegate_);

        //otherwise, serialize anonymous class
            info.AddValue("isSerializable", false);
            info.AddValue("method", delegate_.Method);
                new AnonymousClassWrapper
		(delegate_.Method.DeclaringType, delegate_.Target));

    public Delegate Delegate { get { return delegate_; } }

    Delegate delegate_;

    class AnonymousClassWrapper : ISerializable
        internal AnonymousClassWrapper(Type bclass, object bobject)
            this.type = bclass;
            this.obj = bobject;

        internal AnonymousClassWrapper(SerializationInfo info, StreamingContext context)
            Type classType = (Type)info.GetValue("classType", typeof(Type));
            obj = Activator.CreateInstance(classType);

            foreach (FieldInfo field in classType.GetFields())
                //If the field is a delegate
                if (typeof(Delegate).IsAssignableFrom(field.FieldType))
				(field.Name, typeof(SerializeDelegate)))
                //If the field is an anonymous class
                else if(!field.FieldType.IsSerializable)
				(field.Name, typeof(AnonymousClassWrapper)))
                    field.SetValue(obj, info.GetValue(field.Name, field.FieldType));

        void ISerializable.GetObjectData
		(SerializationInfo info, StreamingContext context)
            info.AddValue("classType", type);

            foreach (FieldInfo field in type.GetFields())
                //See corresponding comments above
                if (typeof(Delegate).IsAssignableFrom(field.FieldType))
                    info.AddValue(field.Name, new SerializeDelegate
                else if (!field.FieldType.IsSerializable)
                    info.AddValue(field.Name, new AnonymousClassWrapper
				(field.FieldType, field.GetValue(obj)));
                    info.AddValue(field.Name, field.GetValue(obj));

        public Type type; 
        public object obj;


  • 12th February, 2009: Initial post


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Fredrik Norén
CEO Keldyn Interactive
Sweden Sweden
No Biography provided

Comments and Discussions

Questionwhat do i pass to SerializeDelegate() ? Pinmemberserpiccio25-Apr-13 1:38 
GeneralUnable to deserialize Pinmemberpadanfain16-Jun-09 7:21 
GeneralRe: Unable to deserialize Pinmemberchot19-Aug-09 12:40 
GeneralA question... PinprotectorMarc Clifton23-Feb-09 2:37 
Could you provide an example of how to use solution?
[edit]Ummm, ok, I'm blind. There is one line of "Usage", but it's still not very clear to me. Maybe I'm having a brain dead Monday morning.[/edit]
Available for consulting and full time employment. Contact me.

GeneralSerializing/reconstituting delegates Pinmembersupercat912-Feb-09 17:11 
GeneralRe: Serializing/reconstituting delegates Pinmemberchot13-Feb-09 1:27 
GeneralRe: Serializing/reconstituting delegates Pinmembersupercat913-Feb-09 13:21 
GeneralRe: Serializing/reconstituting delegates Pinmemberchot13-Feb-09 15:34 

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