TMutable

Src/Myc.Signals.pas

@@ -6,16 +6,16 @@ uses
     System.SysUtils;
 
 type
-    IMycSubscriber = interface
-        function Notify: Boolean;
-    end;
-
     TSignal = record
         type
+            ISubscriber = interface
+                function Notify: Boolean;
+            end;
+
             TSubscriptionTag = Pointer;
 
             ISignal = interface
-                function Subscribe(Subscriber: IMycSubscriber): TSubscriptionTag;
+                function Subscribe(Subscriber: ISubscriber): TSubscriptionTag;
                 procedure Unsubscribe(Tag: TSubscriptionTag);
             end;
 
@@ -45,38 +45,11 @@ type
         class operator Implicit(const A: ISignal): TSignal; overload;
         class operator Implicit(const A: TSignal): ISignal; overload;
 
-        function Subscribe(Subscriber: IMycSubscriber): TSubscription; inline;
+        function Subscribe(Subscriber: ISubscriber): TSubscription; inline;
 
         class property Null: ISignal read FNull;
     end;
 
-    TEvent = record
-        type
-            IEvent = interface(TSignal.ISignal)
-                procedure Trigger;
-            end;
-
-    {$REGION 'private'}
-    strict private
-        class var
-            FNull: IEvent;
-        class constructor ClassCreate;
-
-    private
-        FEvent: IEvent;
-    {$ENDREGION}
-    public
-        constructor Create(const AEvent: IEvent);
-        class operator Initialize(out Dest: TEvent);
-        class operator Implicit(const A: IEvent): TEvent; overload;
-        class operator Implicit(const A: TEvent): IEvent; overload;
-
-        class property Null: IEvent read FNull;
-
-        function Subscribe(Subscriber: IMycSubscriber): TSignal.TSubscription; inline;
-        procedure Unsubscribe(Tag: Pointer); inline;
-    end;
-
     TState = record
         type
             IState = interface(TSignal.ISignal)
@@ -108,18 +81,54 @@ type
 
         class property Null: IState read FNull;
 
-        function Subscribe(Subscriber: IMycSubscriber): TSignal.TSubscription; inline;
-        procedure Unsubscribe(Tag: Pointer); inline;
+        function Subscribe(Subscriber: TSignal.ISubscriber): TSignal.TSubscription; inline;
 
         property IsSet: Boolean read GetIsSet;
     end;
 
+    // An event is a stateless signal that forwards all notifications to the subscribers.
+    TEvent = record
+        type
+            IEvent = interface(TSignal.ISubscriber)
+                {$REGION 'property access'}
+                function GetSignal: TSignal;
+                {$ENDREGION}
+                property Signal: TSignal read GetSignal;
+            end;
+
+    {$REGION 'private'}
+    strict private
+        class var
+            FNull: IEvent;
+        class constructor ClassCreate;
+
+    private
+        FEvent: IEvent;
+        function GetSignal: TSignal; inline;
+    {$ENDREGION}
+    public
+        constructor Create(const AEvent: IEvent);
+        class operator Initialize(out Dest: TEvent);
+        class operator Implicit(const A: IEvent): TEvent; overload;
+        class operator Implicit(const A: TEvent): IEvent; overload;
+
+        class function CreateEvent: TEvent; static;
+
+        class property Null: IEvent read FNull;
+
+        function Notify: Boolean; inline;
+
+        property Signal: TSignal read GetSignal;
+    end;
+
     // A latch is a specific type of event that, once set, remains set (non-resettable).
     // It becomes set when the internal countdown reaches zero.
     TLatch = record
         type
-            ILatch = interface(IMycSubscriber)
+            ILatch = interface(TSignal.ISubscriber)
+                {$REGION 'property access'}
                 function GetState: TState;
+                {$ENDREGION}
                 property State: TState read GetState;
             end;
 
@@ -153,8 +162,10 @@ type
     // TFlag represents a resettable flag, typically indicating if a State is "dirty" (requiring attention) or "clean".
     TFlag = record
         type
-            IFlag = interface(IMycSubscriber)
+            IFlag = interface(TSignal.ISubscriber)
+                {$REGION 'property access'}
                 function GetState: TState;
+                {$ENDREGION}
                 function Reset: Boolean;
                 property State: TState read GetState;
             end;
@@ -260,16 +271,11 @@ begin
     Result := FState.IsSet;
 end;
 
-function TState.Subscribe(Subscriber: IMycSubscriber): TSignal.TSubscription;
+function TState.Subscribe(Subscriber: TSignal.ISubscriber): TSignal.TSubscription;
 begin
     Result := TSignal.TSubscription.Create(FState, FState.Subscribe(Subscriber));
 end;
 
-procedure TState.Unsubscribe(Tag: Pointer);
-begin
-    FState.Unsubscribe(Tag);
-end;
-
 class operator TState.Implicit(const A: TState): IState;
 begin
     Result := A.FState;
@@ -299,14 +305,19 @@ begin
     FNull := TMycNullEvent.Create();
 end;
 
-function TEvent.Subscribe(Subscriber: IMycSubscriber): TSignal.TSubscription;
+class function TEvent.CreateEvent: TEvent;
 begin
-    Result := TSignal.TSubscription.Create(FEvent, FEvent.Subscribe(Subscriber));
+    Result := TMycEvent.Create;
 end;
 
-procedure TEvent.Unsubscribe(Tag: Pointer);
+function TEvent.GetSignal: TSignal;
 begin
-    FEvent.Unsubscribe(Tag);
+    Result := FEvent.Signal;
+end;
+
+function TEvent.Notify: Boolean;
+begin
+    Result := FEvent.Notify;
 end;
 
 class operator TEvent.Implicit(const A: TEvent): IEvent;
@@ -443,7 +454,7 @@ begin
         FSignal := FNull;
 end;
 
-function TSignal.Subscribe(Subscriber: IMycSubscriber): TSubscription;
+function TSignal.Subscribe(Subscriber: ISubscriber): TSubscription;
 begin
     Result := TSubscription.Create(FSignal, FSignal.Subscribe(Subscriber));
 end;