Follow comments from Xu Wei

paddle/framework/variable.h

@@ -12,6 +12,8 @@
 */
 #pragma once
 
+#include <memory>
+#include <typeindex>
 #include <typeinfo>
 
 namespace paddle {
@@ -26,24 +28,14 @@ class Variable {
 
   template <typename T>
   T* GetMutable() {
-    if (holder_ != nullptr && typeid(T) == holder_->Type()) {
-      return static_cast<T*>(holder_->Ptr());
-    } else {
-      return Reset<T>(new T(), DefaultDeleter<T>());
-    }
+    if (holder_ == nullptr ||
+        std::type_index(typeid(T)) != std::type_index(holder_->Type())) {
+      holder_.reset(new PlaceholderImpl<T>(new T()));
     }
-
-  ~Variable() {
-    if (holder_ != nullptr) delete holder_;
+    return static_cast<T*>(holder_->Ptr());
   }
 
  private:
-  // DefaultDeleter is functor which uses C++'s delete(T*).
-  template <typename T>
-  struct DefaultDeleter {
-    void operator()(T* ptr) { delete ptr; }
-  };
-
   struct Placeholder {
     virtual ~Placeholder() {}
     virtual const std::type_info& Type() const = 0;
@@ -54,34 +46,17 @@ class Variable {
   // parameter of Variable.
   template <typename T>
   struct PlaceholderImpl : public Placeholder {
-    typedef std::function<void(T*)> Deleter;
-
     PlaceholderImpl(T* ptr) : ptr_(ptr), type_(typeid(T)) {}
-    PlaceholderImpl(T* ptr, Deleter d)
-        : ptr_(ptr), type_(typeid(T)), deleter_(d) {}
 
-    virtual ~PlaceholderImpl() {
-      deleter_(ptr_);
-      ptr_ = nullptr;
-    }
     virtual const std::type_info& Type() const { return type_; }
-    virtual void* Ptr() const { return ptr_; }
+    virtual void* Ptr() const { return static_cast<void*>(ptr_.get()); }
 
-    T* ptr_ = nullptr;
+    std::unique_ptr<T> ptr_;
     const std::type_info& type_;
-    std::function<void(T*)> deleter_ = DefaultDeleter<T>();
   };
 
-  template <typename T>
-  T* Reset(T* allocated, typename PlaceholderImpl<T>::Deleter deleter) {
-    if (holder_ != nullptr) {
-      delete holder_;
-    }
-    holder_ = new PlaceholderImpl<T>(allocated, deleter);
-    return allocated;
-  }
-
-  Placeholder* holder_;  // pointers to a PlaceholderImpl object indeed.
+  std::unique_ptr<Placeholder>
+      holder_;  // pointers to a PlaceholderImpl object indeed.
 };
 
 }  // namespace framework