Counts instances of classes

instance_count.h

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+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+
+Copyright(c) 2014 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_INSTANCE_COUNT__
+#define __ETL_INSTANCE_COUNT__
+
+///\defgroup instance_count instance count
+///\ingroup utilities
+
+namespace etl
+{
+  //***************************************************************************
+  /// Inherit from this to count instances of a type.
+  ///\ingroup reference
+  //***************************************************************************
+  template <typename T>
+  class instance_count
+  {
+  public:
+
+    //*************************************************************************
+    /// Construct and add 1.
+    //*************************************************************************
+    instance_count()
+    {
+      ++how_many;
+    }
+
+    //*************************************************************************
+    /// Destruct and subtract 1.
+    //*************************************************************************
+    virtual ~instance_count()
+    {
+      --how_many;
+    }
+
+    //*************************************************************************
+    /// Get how many instances we have.
+    //*************************************************************************
+    inline static size_t get_instance_count()
+    {
+      return how_many;
+    }
+
+  private:
+
+    /// The count for this type.
+    static size_t how_many;
+  };
+
+  /// Initialisation.
+  template <typename T> size_t instance_count<T>::how_many = 0;
+}
+
+#endif
+