Issues #276, #1163 - introduce class IncomingParam

src/plugin/COM_Value.cpp

 /**
  * \file COM_Value.cpp Support for the values used in COM and Automation.
  */
 #include "COM_Value.h"
 #include <stdexcept>
 
 using namespace AdblockPlus::COM;
 
 /*
  * MSDN SysAllocStringLen function http://msdn.microsoft.com/en-us/library/windows/desktop/ms221639%28v=vs.85%29.aspx
@@ skipping 44 matching lines @@
 }
 
 BSTR_Argument::operator std::wstring() const
 {
   if ( !bstr )
   {
     return std::wstring();
   }
   return std::wstring( bstr, SysStringLen( bstr ) );
 }
+
+
+namespace
+{
+  /**
+   * Pre-construction assistant for wstring_Incoming_Param.
+   *
+   * Because wstring_Incoming_Param is a derived class,
+   *   we need to have a wstring value to initialize the base class.
+   */
+  std::wstring construct_Incoming_Param( BSTR b )
+  {
+    if ( !b )
+    {
+      return std::wstring();
+    }
+    return std::wstring( b, SysStringLen( b ) );
+  }
+}
+
+Incoming_Param::Incoming_Param( BSTR b )
+  : std::wstring( construct_Incoming_Param( b ) )
+{
+}