The int type does not allow int as an object

Question

The int type does not allow int as an object

I am using INotifyPropertyChanged to propagate changes in my WinForm application.

In this case, I have code that converts the timestamp of an entire UNIX chain and a System DateTime object. It receives a ConvertEventArgs object, which contains the value of the object and the desired type to convert.

By using INotifyPropertyChanged and adding a dynamic binding to the control, you can provide handlers that feed the DesiredType in the ConvertEventArg object.

I have a base class that I call NotifyBase that includes this static function:

public class NotifyBase {
    public static void UpdateDataBindings(string propertyName
                                            , Control ctl
                                            , object bindingSource
                                            , string bindingPropertyName
                                            , Action<object, ConvertEventArgs> formatFunc = null
                                            , Action<object, ConvertEventArgs> parseFunc = null
                                            , bool clearBefore = true
                                            , bool formattingEnabled = true) {
        var b = new Binding(propertyName, bindingSource, bindingPropertyName, formattingEnabled, DataSourceUpdateMode.OnPropertyChanged);
        if (formatFunc != null) b.Format += (sender, args) => formatFunc(sender,args);
        if (parseFunc != null) b.Format += (sender, args) => parseFunc(sender,args);
        if(clearBefore) ctl.DataBindings.Clear();
        ctl.DataBindings.Add(b)

The base class also implements this:

    public event PropertyChangedEventHandler PropertyChanged;
    protected void SetPropertyField<T>(ref T field, T newValue,
[System.Runtime.CompilerServices.CallerMemberName] string propertyName = "") {
            if (EqualityComparer<T>.Default.Equals(field, newValue)) return;
            field = newValue;
            // Ignoring online conjecture about the need to keep a reference to the event property
            // before invoking it. 
            // 1. this is a single threaded app.
            // 2. documentation clearly says that event handlers should merely be checked for being null.
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

Then I initialize my data. Here is an example with Winform DateTimePicker.

NotifyBase.UpdateDataBindings("Value", TimePickerBox, Config, nameof(Config.UnitTimestamp)
                , (o, args) => { NotifyBase.PropertyTypeChange(args, ReportingTimeZoneInfo); }
                , (o, args) => { NotifyBase.PropertyTypeChange(args, ReportingTimeZoneInfo); });

PropertyTypeChange ConvertEventArg , :

Type u = Nullable.GetUnderlyingType(carg.DesiredType);
if (carg.DesiredType == typeof(DateTime) || u == typeof(DateTime)) {
    if (u == null) {
        if (carg.Value is int) {
            carg.Value = epoch.AddSeconds((int) carg.Value);
        }
        else if (carg.Value is DateTime) carg.Value = carg.Value; // do not throw if type is already the expected type.
        else throw new ArgumentOutOfRangeException("Value type conversion to DateTime is not supported.");
    } else {
        DateTime tp;
        if (carg.Value is int) {
            tp = epoch.AddSeconds((int) carg.Value);
        }
        else if (carg.Value is DateTime) tp = (DateTime) carg.Value; // do not throw if type is already the expected type.
        else throw new ArgumentOutOfRangeException("Value type conversion to DateTime is not supported.");
        carg.Value = tp.MakeNullable<DateTime>();
    }
}