How should we generate TrySet

[JohanLarsson]

• Always set
• Notify if different.
• EqualityComparer or RuntimeHelpers?
• Names? Method & parameters.

/cc @jnm2

[JohanLarsson]

Maybe:

protected bool TrySet<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
    if (EqualityComparer<T>.Default.Equals(field, value))
    {
        field = value;
        return false;
    }

    field = value;
    this.OnPropertyChanged(propertyName);
    return true;
}

[jnm2]

The two candidates I like best (right now):

// Downside: boxing

protected bool TrySet<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
    if (RuntimeHelpers.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

// Downside: can fail to raise the event and return true for things that an observer could care
// about which are ignored by Equals.

protected bool TrySet<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
    var shouldNotify = !EqualityComparer<T>.Default.Equals(field, value);
    field = value;
    if (shouldNotify) OnPropertyChanged(propertyName);
    return shouldNotify;
}