equality on the sender of an event

Question

I have an interface for a UI widget, two of which are attributes of a presenter.

public IMatrixWidget NonProjectActivityMatrix {
        set {
            // validate the incoming value and set the field
            _nonProjectActivityMatrix = value;
            ....
            // configure & load non-project activities
     }

public IMatrixWidget ProjectActivityMatrix {
        set {
            // validate the incoming value and set the field
            _projectActivityMatrix = value;
            ....
            // configure & load project activities
   }

The widget has an event that both presenter objects subscribe to, and so there is an event handler in the presenter like so:

public void OnActivityEntry(object sender, EntryChangedEventArgs e) {
    // calculate newTotal here
    ....
        if (ReferenceEquals(sender, _nonProjectActivityMatrix)) {
            _nonProjectActivityMatrix.UpdateTotalHours(feedback.ActivityTotal);
        }

        else if (ReferenceEquals(sender, _projectActivityMatrix)) {
            _projectActivityMatrix.UpdateTotalHours(feedback.ActivityTotal);
        }
        else {
            // ERROR - we should never be here
        }
    }

The problem is that the ReferenceEquals on the sender fails, even though it is the implemented widget that is the sender - the same implemented widget that was set to the presenter attribute!

Can anyone spot what the problem / fix is?

Cheers, Berryl

I didn't know you could edit nicely. Cool. Here is the event raising code:

void OnGridViewNumericUpDownEditingControl_ValueChanged(object sender, EventArgs e)
    {
 // omitted to save sapce

        if (EntryChanged == null) return;

        var args = new EntryChangedEventArgs(activityID, dayID, Convert.ToDouble(amount));
        EntryChanged(this, args);
    }

Here is the debugger dump of the presenter attribute, sans namespace info:

?_nonProjectActivityMatrix
{WinPresentation.Widgets.MatrixWidgetDgv}
[WinPresentation.Widgets.MatrixWidgetDgv]: {WinPresentation.Widgets.MatrixWidgetDgv}

Here is the debugger dump of the sender:

?sender
{WinPresentation.Widgets.MatrixWidgetDgv}
base {Core.GUI.Widgets.Lookup.MatrixWidgetBase<Core.GUI.Widgets.Lookup.DynamicDisplayDto>}: {WinPresentation.Widgets.MatrixWidgetDgv}
_configuration: {Domain.Presentation.Timesheet.Matrix.WeeklyMatrixConfiguration}
_wrappedWidget: {Win.Widgets.DataGridViewDynamicLookupWidget}
AllowUserToAddRows: true
ColumnCount: 11
Count: 4
EntryChanged: {Method = {Void OnActivityEntry(System.Object, Smack.ConstructionAdmin.Domain.Presentation.Timesheet.Matrix.EntryChangedEventArgs)}}
SelectedCell: {DataGridViewNumericUpDownCell { ColumnIndex=3, RowIndex=3 }}
SelectedCellValue: "0.00"
SelectedColumn: {DataGridViewNumericUpDownColumn { Name=MONDAY, Index=3 }}
SelectedItem: {'AdministrativeActivity: 130-04', , AdministrativeTime, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00}

• Berryl

Answer 1

Off the top of my head I can think of these reasons why ReferenceEquals will return false:

• sender is null - Verify that the widget sends this as the sender parameter when raising the event.
• The widget is not assigned to the presenter for some reason, so it is null
• sender is not what you think it is (how have you verified that it is indeed the sender you expect)
• The widget is implemented as a struct, not a class

There may be more, but this is where I would start (in that order).

Update: one thing that catches my eye is this:

_wrappedWidget: {Win.Widgets.DataGridViewDynamicLookupWidget}

Could it be that sender is an object that wraps your widget? If that is the case, ReferenceEquals will naturally return false when doing the comparison.