fixes EETypeLoadException issue: export class DelegateCommand (#18)

* fixes EETypeLoadException issue: export class DelegateCommand

* weak-reference in C++/CX

* WeakRef in C# codebase

* UTF-8-BOM

* spaces in macro

* resolve some comments from the offline review

* format

* rename file

src/CalcViewModel/Common/DelegateCommand.h

@@ -7,18 +7,14 @@ namespace CalculatorApp
 {
     namespace Common
     {
-        template <typename TTarget>
+        public delegate void DelegateCommandHandler(Platform::Object ^ parameter);
-        ref class DelegateCommand : public Windows::UI::Xaml::Input::ICommand
-        {
-            internal :
 
-                typedef void (TTarget::*CommandHandlerFunc)(Platform::Object ^);
+        public ref class DelegateCommand sealed : public Windows::UI::Xaml::Input::ICommand
-
-            DelegateCommand(TTarget ^ target, CommandHandlerFunc func)
-                : m_weakTarget(target)
-                , m_function(func)
         {
-            }
+        public:
+            DelegateCommand(DelegateCommandHandler ^ handler)
+                : m_handler(handler)
+            {}
 
         private:
             // Explicit, and private, implementation of ICommand, this way of programming makes it so
@@ -27,11 +23,7 @@ namespace CalculatorApp
             // code in the app calling Execute.
             virtual void ExecuteImpl(Platform::Object ^ parameter) sealed = Windows::UI::Xaml::Input::ICommand::Execute
             {
-                TTarget ^ target = m_weakTarget.Resolve<TTarget>();
+                m_handler->Invoke(parameter);
-                if (target)
-                {
-                    (target->*m_function)(parameter);
-                }
             }
 
             virtual bool CanExecuteImpl(Platform::Object ^ parameter) sealed = Windows::UI::Xaml::Input::ICommand::CanExecute
@@ -52,17 +44,25 @@ namespace CalculatorApp
             }
 
         private:
+            DelegateCommandHandler ^ m_handler;
 
             event Windows::Foundation::EventHandler<Platform::Object ^> ^ m_canExecuteChanged;
-
-            CommandHandlerFunc m_function;
-            Platform::WeakReference m_weakTarget;
         };
 
         template <typename TTarget, typename TFuncPtr>
-            DelegateCommand<TTarget> ^ MakeDelegate(TTarget ^ target, TFuncPtr&& function) {
+        DelegateCommandHandler ^ MakeDelegateCommandHandler(TTarget ^ target, TFuncPtr&& function)
-                return ref new DelegateCommand<TTarget>(target, std::forward<TFuncPtr>(function));
+        {
+            Platform::WeakReference weakTarget(target);
+            return ref new DelegateCommandHandler([weakTarget, function=std::forward<TFuncPtr>(function)](Platform::Object ^ param)
+                {
+                    TTarget ^ thatTarget = weakTarget.Resolve<TTarget>();
+                    if (nullptr != thatTarget)
+                    {
+                        (thatTarget->*function)(param);
+                    }
+                }
+            );
+        }
+    }
 }
 
-    }
-}

src/CalcViewModel/Common/Utils.h

@@ -168,11 +168,22 @@ public:
 // The variable member generated by this macro should not be used in the class code, use the
 // property getter instead.
 #define COMMAND_FOR_METHOD(p, m)                                                                                                                               \
-    property Windows::UI::Xaml::Input::ICommand^ p {\
+    property Windows::UI::Xaml::Input::ICommand ^ p                                                                                                            \
-    Windows::UI::Xaml::Input::ICommand^ get() {\
+    {                                                                                                                                                          \
-    if (!donotuse_##p) {\
+        Windows::UI::Xaml::Input::ICommand ^ get()                                                                                                             \
-    donotuse_##p = CalculatorApp::Common::MakeDelegate(this, &m);\
+        {                                                                                                                                                      \
-    } return donotuse_##p; }} private: Windows::UI::Xaml::Input::ICommand^ donotuse_##p;                                                                                                         \
+            if (!donotuse_##p)                                                                                                                                 \
+            {                                                                                                                                                  \
+                donotuse_##p = ref new CalculatorApp::Common::DelegateCommand(                                                                                 \
+                    CalculatorApp::Common::MakeDelegateCommandHandler(this, &m)                                                                                \
+                );                                                                                                                                             \
+            }                                                                                                                                                  \
+            return donotuse_##p;                                                                                                                               \
+        }                                                                                                                                                      \
+    }                                                                                                                                                          \
+                                                                                                                                                               \
+private:                                                                                                                                                       \
+    Windows::UI::Xaml::Input::ICommand ^ donotuse_##p;                                                                                                         \
                                                                                                                                                                \
 public:
 

src/Calculator/Calculator.csproj

@@ -151,11 +151,11 @@
     <Compile Include="Converters\ItemSizeToVisibilityConverter.cs" />
     <Compile Include="Converters\RadixToStringConverter.cs" />
     <Compile Include="Converters\VisibilityNegationConverter.cs" />
-    <Compile Include="DelegateCommand.cs" />
     <Compile Include="EquationStylePanelControl.xaml.cs">
       <DependentUpon>EquationStylePanelControl.xaml</DependentUpon>
     </Compile>
     <Compile Include="KeyGraphFeaturesTemplateSelector.cs" />
+    <Compile Include="Utils\DelegateCommandUtils.cs" />
     <Compile Include="Views\Calculator.xaml.cs">
       <DependentUpon>Calculator.xaml</DependentUpon>
     </Compile>

src/Calculator/DelegateCommand.cs

@@ -1,35 +0,0 @@
-using System;
-
-namespace CalculatorApp.Common
-{
-    internal class DelegateCommand<TTarget> : System.Windows.Input.ICommand
-    {
-        public delegate void CommandHandlerFunc(object obj);
-
-        public DelegateCommand(TTarget target, CommandHandlerFunc func)
-        {
-            m_weakTarget = new WeakReference(target);
-            m_function = func;
-        }
-
-        public event EventHandler CanExecuteChanged;
-
-        public bool CanExecute(object parameter)
-        {
-            return true;
-        }
-
-        public void Execute(object parameter)
-        {
-            object target = m_weakTarget.Target;
-            if (target != null && target is TTarget)
-            {
-                m_function(parameter);
-            }
-        }
-
-        private CommandHandlerFunc m_function;
-        private WeakReference m_weakTarget;
-    }
-}
-

src/Calculator/Utils/DelegateCommandUtils.cs

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using CalculatorApp.Common;
+
+namespace CalculatorApp.Utils
+{
+    static class DelegateCommandUtils
+    {
+        public static DelegateCommand MakeDelegateCommand<TTarget>(TTarget target, DelegateCommandHandler handler)
+            where TTarget : class
+        {
+            WeakReference weakTarget = new WeakReference(target);
+            return new DelegateCommand(param =>
+            {
+                TTarget thatTarget = weakTarget.Target as TTarget;
+                if(null != thatTarget)
+                {
+                    handler.Invoke(param);
+                }
+            });
+        }
+    }
+}
+

src/Calculator/Views/Calculator.xaml.cs

@@ -9,6 +9,7 @@ using CalculatorApp;
 using CalculatorApp.Common;
 using CalculatorApp.Converters;
 using CalculatorApp.Controls;
+using CalculatorApp.Utils;
 using CalculatorApp.ViewModel;
 
 using Windows.Foundation;
@@ -140,7 +141,7 @@ namespace CalculatorApp
             {
                 if (donotuse_HistoryButtonPressed == null)
                 {
-                    donotuse_HistoryButtonPressed = new DelegateCommand<Calculator>(this, ToggleHistoryFlyout);
+                    donotuse_HistoryButtonPressed = DelegateCommandUtils.MakeDelegateCommand(this, ToggleHistoryFlyout);
                 }
                 return donotuse_HistoryButtonPressed;
             }

src/Calculator/Views/CalculatorScientificAngleButtons.xaml.cs

@@ -11,6 +11,7 @@ using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Diagnostics;
 using CalculatorApp;
+using CalculatorApp.Utils;
 using CalculatorApp.ViewModel;
 
 using Windows.Foundation;
@@ -47,7 +48,7 @@ namespace CalculatorApp
             {
                 if (donotuse_ButtonPressed == null)
                 {
-                    donotuse_ButtonPressed = new CalculatorApp.Common.DelegateCommand<CalculatorScientificAngleButtons>(this, OnAngleButtonPressed);
+                    donotuse_ButtonPressed = DelegateCommandUtils.MakeDelegateCommand(this, OnAngleButtonPressed);
                 }
                 return donotuse_ButtonPressed;
             }

src/Calculator/Views/GraphingCalculator/GraphingCalculator.xaml.cs

@@ -9,6 +9,7 @@ using CalculatorApp;
 using CalculatorApp.Common;
 using CalculatorApp.Common.Automation;
 using CalculatorApp.Controls;
+using CalculatorApp.Utils;
 using CalculatorApp.ViewModel;
 //using CalcManager.NumberFormattingUtils;
 using GraphControl;
@@ -114,7 +115,7 @@ namespace CalculatorApp
             {
                 if (donotuse_ZoomOutButtonPressed == null)
                 {
-                    donotuse_ZoomOutButtonPressed = new DelegateCommand<GraphingCalculator>(this, OnZoomOutCommand);
+                    donotuse_ZoomOutButtonPressed = DelegateCommandUtils.MakeDelegateCommand(this, OnZoomOutCommand);
                 }
                 return donotuse_ZoomOutButtonPressed;
             }
@@ -127,7 +128,7 @@ namespace CalculatorApp
             {
                 if (donotuse_ZoomInButtonPressed == null)
                 {
-                    donotuse_ZoomInButtonPressed = new DelegateCommand<GraphingCalculator>(this, OnZoomInCommand);
+                    donotuse_ZoomInButtonPressed = DelegateCommandUtils.MakeDelegateCommand(this, OnZoomInCommand);
                 }
                 return donotuse_ZoomInButtonPressed;
             }

src/Calculator/Views/StateTriggers/CalculatorProgrammerDisplayPanel.xaml.cs

@@ -2,6 +2,7 @@
 using System.Windows.Input;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
+using CalculatorApp.Utils;
 
 // The User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
 
@@ -16,8 +17,7 @@ namespace CalculatorApp
             {
                 if (donotuse_BitLengthButtonPressed == null)
                 {
-                    donotuse_BitLengthButtonPressed =
+                    donotuse_BitLengthButtonPressed = DelegateCommandUtils.MakeDelegateCommand(this, OnBitLengthButtonPressed);
-                        new Common.DelegateCommand<CalculatorProgrammerDisplayPanel>(this, OnBitLengthButtonPressed);
                 }
                 return donotuse_BitLengthButtonPressed;
             }