值转换器vs附加属性

Question

In case of long lines in xaml with bool to visibility converters I find this question interesting. What will do the job better: value converter or attached property?

Using value converter from bool to Visibility:

Visibility="{Binding IsCommentPreviewVisible,Converter={StaticResource myBoolToVisibilityConverter}}" 

or using attached property:

ap:BoolVisibility.Visible="{Binding IsCommentPreviewVisible}"

where VisibleChanged internally handle Visibility of FrameworkElement .

Answer 1

Custom attached properties are generally good for when you need to set a property for a class other than the defining class.

Take Canvas.Left , Canvas.Top , Canvas.Right , Canvas.Bottom for example, these properties are for the parent element to use, not specifically for the defining element. You would use Canvas. attached properties to define the positioning of elements within another element (a Canvas ).

It might be worth reading the documentation .

Converters on the other hand offer you the means of quite simply, converting one data type to another on the UI. That being said, you can still use an attached property to mimic the behaviour of a converter.

If you need to do anything culture aware then an IValueConverter has this built in, an attached property does not. See the documentation

Personally I tend to steer away from attached properties unless I need to attach a property which a parent class will need to use. It's difficult to provide a real example because I rarely use them, if ever.