FSI WPF Event Loop

Question

Is the WPF event loop in this answer still good for FSI (except rethrowwhich now reraise)? The answer is from 2008, and I'm not sure if there are any “best” implementations. If not what would it be?

My understanding is that the default implementation for WinForms.

Answer 1

Yes, by default for Winforms, I quite often use WpfEventLoop, the code below,

#I "c:/Program Files/Reference Assemblies/Microsoft/Framework/v3.0"
#I "C:/WINDOWS/Microsoft.NET/Framework/v3.0/WPF/"
#r "PresentationCore.dll"
#r "PresentationFramework.dll"
#r "WindowsBase.dll"

module WPFEventLoop =     
    open System    
    open System.Windows    
    open System.Windows.Threading    
    open Microsoft.FSharp.Compiler.Interactive    
    open Microsoft.FSharp.Compiler.Interactive.Settings    

    type RunDelegate<'b> = delegate of unit -> 'b     
    let Create() =         
        let app  =             
            try                 
                // Ensure the current application exists. This may fail, if it already does.                
                let app = new Application() in                 
                // Create a dummy window to act as the main window for the application.                
                // Because we're in FSI we never want to clean this up.                
                new Window() |> ignore;                 
                app              
            with :? InvalidOperationException -> Application.Current        
        let disp = app.Dispatcher        
        let restart = ref false        
        { new IEventLoop with             
            member x.Run() =                    
                app.Run() |> ignore                 
                !restart             

            member x.Invoke(f) =                  
                try 
                    disp.Invoke(DispatcherPriority.Send,new RunDelegate<_>(fun () -> box(f ()))) |> unbox                 
                with e -> eprintf "\n\n ERROR: %O\n" e; reraise()             

            member x.ScheduleRestart() =   ()                 
            //restart := true;                 
            //app.Shutdown()        
         }     

    let Install() = fsi.EventLoop <-  Create()

WPFEventLoop.Install()

Test code

open System
open System.Windows
open System.Windows.Controls

let window = new Window(Title = "Simple Test", Width = 800., Height = 600.)
window.Show()

let textBox = new TextBox(Text = "F# is fun")
window.Content <- textBox

Let me know if that helps.

-Fahad