C# – Remove handlers on disposing object

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I can think of a few messy ways to solve this, but it strikes me that there should be a far more elegant solution than those which I've already come up with.

What's the most appropriate way for an object to cleanse itself of all of its event handlers prior to being disposed. It's a shame the event handler can't be enumerated upon.

In theory, is it considered more correct for the code adding the handler to an object to remember to remove it than assuming the object will clean itself up before it goes out of scope?

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In theory, is it considered more correct for the code adding the handler to an object to remember to remove it than assuming the object will clean itself up before it goes out of scope?

To the above question, I'll have to say yes. The basic theory about events is that the event firer shouldn't be responsible for managing its own handlers; whoever added the event should do cleanup.

Related Solutions

C# – How to create a new object instance from a Type

The Activator class within the root System namespace is pretty powerful.

There are a lot of overloads for passing parameters to the constructor and such. Check out the documentation at:

http://msdn.microsoft.com/en-us/library/system.activator.createinstance.aspx

or (new path)

https://docs.microsoft.com/en-us/dotnet/api/system.activator.createinstance

Here are some simple examples:

ObjectType instance = (ObjectType)Activator.CreateInstance(objectType);

ObjectType instance = (ObjectType)Activator.CreateInstance("MyAssembly","MyNamespace.ObjectType");

C# – How to remove all event handlers from an event

I found a solution on the MSDN forums. The sample code below will remove all Click events from button1.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        button1.Click += button1_Click;
        button1.Click += button1_Click2;
        button2.Click += button2_Click;
    }

    private void button1_Click(object sender, EventArgs e)  => MessageBox.Show("Hello");
    private void button1_Click2(object sender, EventArgs e) => MessageBox.Show("World");
    private void button2_Click(object sender, EventArgs e)  => RemoveClickEvent(button1);

    private void RemoveClickEvent(Button b)
    {
        FieldInfo f1 = typeof(Control).GetField("EventClick", 
            BindingFlags.Static | BindingFlags.NonPublic);

        object obj = f1.GetValue(b);
        PropertyInfo pi = b.GetType().GetProperty("Events",  
            BindingFlags.NonPublic | BindingFlags.Instance);

        EventHandlerList list = (EventHandlerList)pi.GetValue(b, null);
        list.RemoveHandler(obj, list[obj]);
    }
}

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Related Solutions

C# – How to create a new object instance from a Type

C# – How to remove all event handlers from an event

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