如何在视图模型上使用DelegateCommand？

是否有任何示例说明如何在用F＃编写的视图模型上调用DelegateCommand？

我已经找到了一个DelegateCommand执行下面的代码在这里：

type DelegateCommand<a>(execute : 'a -> unit, ?canExecute : 'a  ->  bool) =
  let event = Event<_,_>()
  interface ICommand with
    member this.CanExecute(param : obj) =
      if canExecute.IsSome then
        canExecute.Value(param :> 'a)
      else true
    member this.Execute (param : obj) =
      execute(param :> 'a)

但是，对于F＃还是陌生的，我不确定是否应该使用此实现，或者是否应该使用其他方法。

这是我确定如何执行DelegateCommand后想要执行的测试：

module CreateProfileViewModel.Tests

open FsUnit
open NUnit.Framework
open CreateProfile.UILogic

[<Test>]
let ``create profile`` () =

    // Setup
    let viewModel = ViewModel()
    viewModel.FirstName <- "Scott"
    viewModel.LastName <- "Nimrod"

    // Test
    viewModel.Submit.Execute();

    // Verify
    let expected = false // TODO - implement some state-change
    expected |> should equal true

我的视图模型如下：

module CreateProfile

open Core.UILogic

type ViewModel() =
    inherit ViewModelBase()
    let mutable firstName = ""
    let mutable lastName = ""

    member this.FirstName
        with get() = firstName 
        and set(value) =
            firstName <- value
            base.NotifyPropertyChanged(<@ this.FirstName @>)

    member this.LastName
        with get() = lastName 
        and set(value) =
            lastName <- value
            base.NotifyPropertyChanged(<@ this.LastName @>)

我有以下基本视图模型：

module Core.UILogic

open System.ComponentModel
open Microsoft.FSharp.Quotations.Patterns

type ViewModelBase () =
    let propertyChanged = 
        Event<PropertyChangedEventHandler,PropertyChangedEventArgs>()

    let getPropertyName = function 
        | PropertyGet(_,pi,_) -> pi.Name
        | _ -> invalidOp "Expecting property getter expression"

    interface INotifyPropertyChanged with
        [<CLIEvent>]
        member this.PropertyChanged = propertyChanged.Publish

    member private this.NotifyPropertyChanged propertyName = 
        propertyChanged.Trigger(this,PropertyChangedEventArgs(propertyName))

    member this.NotifyPropertyChanged quotation = 
        quotation |> getPropertyName |> this.NotifyPropertyChanged

更新：

我已将MVVM项目模板中为F＃定义的RelayCommand修改为以下内容：

module UILogic.Interaction

open System
open System.Windows
open System.Windows.Input
open System.ComponentModel

type DelegateCommand (action:(obj -> unit), canExecute:(obj -> bool)) =
    let event = new DelegateEvent<EventHandler>()
    interface ICommand with
        [<CLIEvent>]
        member this.CanExecuteChanged = event.Publish
        member this.CanExecute arg = canExecute(arg)
        member this.Execute arg = action(arg)

然后，我如下更新了我的视图模型：

module CreateProfile.UILogic

open UILogic.State
open UILogic.Interaction

type ViewModel() =
    inherit ViewModelBase()

    let mutable _firstName = ""
    let mutable _lastName = ""
    let mutable _submitted = false

    member this.FirstName
        with get() = _firstName 
        and set(value) =
            _firstName <- value
            base.NotifyPropertyChanged(<@ this.FirstName @>)

    member this.LastName
        with get() = _lastName 
        and set(value) =
            _lastName <- value
            base.NotifyPropertyChanged(<@ this.LastName @>)

    member this.IsSubmitted
        with get() = _submitted
        and set(value) = _submitted <- value

    member this.Submit =
        new DelegateCommand ((fun _ -> this.IsSubmitted <- true), (fun _ -> true))

但是，我不确定如何在Submit（DelegateCommand）上调用Execute函数：

module CreateProfileViewModel.Tests

open FsUnit
open NUnit.Framework
open UILogic.State
open CreateProfile.UILogic

[<Test>]
let ``create profile`` () =

    // Setup
    let viewModel = ViewModel()
    viewModel.FirstName <- "Scott"
    viewModel.LastName <- "Nimrod"

    // Test
    ignore viewModel.Submit.Execute(); // How to invoke execute?

    // Verify
    viewModel.IsSubmitted |> should equal true

我知道这很简单，但是老实说我不知道​​如何做到这一点。

有什么建议么？