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WPF DepdencyProperty

Declaring WPF DependencyProperty in F#

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// Consider we have a class "WaterMarkTextBox" and it requires
// a WaterMarkText property.
// Declare the static field for DependencyProperty    
static let WaterMarkTextProperty = DependencyProperty.Register("WaterMarkText", typeof<string>, 
typeof<WaterMarkTextBox>, new PropertyMetadata(String.Empty))

// Gets / Sets the WaterMarkText
member x.WaterMarkText
    with get() = x.GetValue(WaterMarkTextProperty) :?> string
    and set(v) = x.SetValue(WaterMarkTextProperty, v)

// Consider we have a PropertyMetadata for an ItemsSource property 
// with a callback
// Below is the code for ItemsSource Dependency Property
static let itemsSourceMetadata = 
        new PropertyMetadata
            ( null, new PropertyChangedCallback
                ( fun dpo args ->
                    (
                        let box = dpo :?> SearchBox
                        if args.NewValue <> null then
                            box.OnItemsSourceChanged(args.NewValue :?> IEnumerable)
                    )
                )                 
            )
static let ItemsSourceProperty = DependencyProperty.Register("ItemsSource", typeof<IEnumerable>, 
typeof<SearchBox>, itemsSourceMetadata)

member private x.OnItemsSourceChanged(itemsSource : IEnumerable) =
   (...)
val typeof<'T> : System.Type

Full name: Microsoft.FSharp.Core.Operators.typeof
Multiple items
val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

--------------------
type string = System.String

Full name: Microsoft.FSharp.Core.string
module String

from Microsoft.FSharp.Core
val set : elements:seq<'T> -> Set<'T> (requires comparison)

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.set
val box : value:'T -> obj

Full name: Microsoft.FSharp.Core.Operators.box
// Gets / Sets the ItemsSource
member x.ItemsSource
   with get() = x.GetValue(ItemsSourceProperty) :?> IEnumerable
   and set(v) = x.SetValue(ItemsSourceProperty, v)
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Link:http://fssnip.net/3k
Posted:6 years ago
Author:Fahad
Tags: wpf