changed IObservable<T> to (an overloaded!) anonymous method type

MainViewModel.pas

@@ -29,9 +29,12 @@   TViewModel = class(TComponent)
     fTickets: TList<TTicket>;
     fAvailableCountries: TArray<string>;
     fCountry: IObservable<string>;
+    fActive: IObservable<Boolean>;
 
     function GetLastName: string;
     procedure SetLastName(const value: string);
+    function GetActive: Boolean;
+    procedure SetActive(const value: Boolean);
   public
     constructor Create(const firstName, lastName: string); reintroduce;
     destructor Destroy; override;
@@ -53,6 +56,8 @@   TViewModel = class(TComponent)
 
     property AvailableCountries: TArray<string> read fAvailableCountries;
     property Country: IObservable<string> read fCountry;
+
+    property Active: Boolean read GetActive write SetActive;
   end;
 
 implementation
@@ -77,19 +82,19 @@ constructor TViewModel.Create(const firstName, lastName: string);
   fFullName := TDependentObservable<string>.Create(
     function: string
     begin
-      Result := fFirstName.Value + ' ' + fLastName.Value;
+      Result := fFirstName + ' ' + fLastName;
     end);
 
   // Example 2
-  fNumberOfClicks := TObservable<Integer>.Create;
+  fNumberOfClicks := TObservable<Integer>.Create();
   fHasClickedTooManyTimes := TDependentObservable<Boolean>.Create(
     function: Boolean
     begin
-      Result := fNumberOfClicks.Value >= 3;
+      Result := fNumberOfClicks >= 3;
     end);
 
   // Example 3
-  fChosenTicket := TObservable<TTicket>.Create;
+  fChosenTicket := TObservable<TTicket>.Create();
   fTickets := TObjectList<TTicket>.Create;
   fTickets.AddRange([
     TTicket.Create('Economy', 199.95),
@@ -98,7 +103,10 @@ constructor TViewModel.Create(const firstName, lastName: string);
 
   // Example 4
   fAvailableCountries := TArray<string>.Create('AU', 'NZ', 'US');
-  fCountry := TObservable<string>.Create;
+  fCountry := TObservable<string>.Create();
+
+  // Example 5;
+  fActive := TObservable<Boolean>.Create(True);
 end;
 
 destructor TViewModel.Destroy;
@@ -107,29 +115,39 @@ destructor TViewModel.Destroy;
   inherited;
 end;
 
+function TViewModel.GetActive: Boolean;
+begin
+  Result := fActive;
+end;
+
 function TViewModel.GetLastName: string;
 begin
-  Result := fLastName.Value;
+  Result := fLastName;
 end;
 
 procedure TViewModel.RegisterClick;
 begin
-  fNumberOfClicks.Value := fNumberOfClicks.Value + 1;
+  fNumberOfClicks(fNumberOfClicks + 1);
 end;
 
 procedure TViewModel.ResetClicks;
 begin
-  fNumberOfClicks.Value := 0;
+  fNumberOfClicks(0);
 end;
 
 procedure TViewModel.ResetTicket;
 begin
-  fChosenTicket.Value := nil;
+  fChosenTicket(nil);
+end;
+
+procedure TViewModel.SetActive(const value: Boolean);
+begin
+  fActive(value);
 end;
 
 procedure TViewModel.SetLastName(const value: string);
 begin
-  fLastName.Value := value;
+  fLastName(value);
 end;
 
 end.

ObservableTests.pas

@@ -40,23 +40,23 @@ procedure TObservableTests.DependentObservableClearsOldDependencies;
     function: string
     begin
       Inc(count);
-      if a.Value then
-        Result := b.Value
+      if a then
+        Result := b
       else
-        Result := c.Value
+        Result := c
     end);
   count := 0;
-  CheckEquals('false', o.Value);
+  CheckEquals('false', o);
   CheckEquals(0, count);
-  b.Value := 'TRUE';
+  b('TRUE');
   CheckEquals(0, count);
-  c.Value := 'FALSE';
-  CheckEquals('FALSE', o.Value);
+  c('FALSE');
+  CheckEquals('FALSE', o);
   CheckEquals(1, count);
-  a.Value := True;
-  CheckEquals('TRUE', o.Value);
+  a(True);
+  CheckEquals('TRUE', o);
   CheckEquals(2, count);
-  c.Value := 'false';
+  c('false');
   CheckEquals(2, count);
 end;
 
@@ -67,8 +67,8 @@ procedure TObservableTests.DependentObservableEvaluatesOnlyOnceAfterChange;
 begin
   count := 0;
   o := TDependentObservable<string>.Create(function: string begin Inc(count); Result := 'test' end);
-  CheckEquals('test', o.Value);
-  CheckEquals('test', o.Value);
+  CheckEquals('test', o);
+  CheckEquals('test', o);
   CheckEquals(1, count);
 end;
 
@@ -77,39 +77,39 @@ procedure TObservableTests.DependentObservableReturnsValue;
   o: IObservable<string>;
 begin
   o := TDependentObservable<string>.Create(function: string begin Result := 'test' end);
-  CheckEquals('test', o.Value);
+  CheckEquals('test', o);
 end;
 
 procedure TObservableTests.DependentObservableUpdatesValueWhenDependencyChanges;
 var
   o1, o2: IObservable<string>;
   called: Boolean;
 begin
-  o1 := TObservable<string>.Create;
-  o2 := TDependentObservable<string>.Create(function: string begin Result := o1.Value; called := True; end);
-  CheckEquals('', o2.Value);
+  o1 := TObservable<string>.Create();
+  o2 := TDependentObservable<string>.Create(function: string begin Result := o1; called := True; end);
+  CheckEquals('', o2);
   called := False;
-  o1.Value := 'test';
+  o1('test');
   Check(called);
-  CheckEquals('test', o2.Value);
+  CheckEquals('test', o2);
 end;
 
 procedure TObservableTests.ObservableReturnsValue;
 var
   o: IObservable<string>;
 begin
   o := TObservable<string>.Create('test');
-  CheckEquals('test', o.Value);
+  CheckEquals('test', o);
 end;
 
 procedure TObservableTests.ObservableSetValueChangesValue;
 var
   o: IObservable<string>;
 begin
-  o := TObservable<string>.Create;
-  CheckEquals('', o.Value);
-  o.Value := 'test';
-  CheckEquals('test', o.Value);
+  o := TObservable<string>.Create();
+  CheckEquals('', o);
+  o('test');
+  CheckEquals('test', o);
 end;
 
 initialization

SimpleMVVM.Binding.pas

@@ -164,7 +164,7 @@ function CreateObservable(instance: TObject;
       if StartsText('IObservable<', prop.PropertyType.Name) then
       begin
         Result := prop.GetValue(instance).AsInterface as IObservable;
-        typ := prop.PropertyType.GetMethod('GetValue').ReturnType;
+        typ := prop.PropertyType.BaseType.GetMethod('Invoke').ReturnType;
       end
       else
       begin