Question

I’m looking through some existing code in a project I’m working on, and I found a class that is implemented as:

public class ThingOne
{
    private int A;

    private int B;

    [NonSerialized]
    private System.Timers.Timer timer1;
}

Shouldn’t it look more like this?

[Serializable]
public class ThingOne
{
    private int A;

    private int B;

    [NonSerialized]
    private System.Timers.Timer timer1;
}

Or is there some additional benefit to adding [NonSerialized] even when the class itself is not Serializable?

Answer 1

NonSerialized will have no effect when Serializable is not used. By default, classes and their members are non-serializable.

The only advantage of declaring something NonSerialized when the class isn’t serialized is under the circumstances that the class is inherited by a Serialized object, and then the inherited member will be non-serializable.

From MSDN:

‘NonSerialized’ attribute will not
affect this member because its
containing class is not exposed as
‘Serializable’.

By default, classes and their members are non-serializable. The NonSerializedAttribute attribute is only needed if a member of a serializable class should not be serialized.