Can I have std::vector store these subclasses mixed?

From: Eric Lilja (ericliljaNoSpam_at_yahoo.com)
Date: 02/26/05 

Date: Sat, 26 Feb 2005 10:35:28 +0100

Hello, in my program I am reading a text file that has format:
option=value
There are several types of options and they expect values of different types
(mostly strings or integers). I made a templated base class Option and had
my different options derive from Option instantiated for their type (i.e.,
class LongOption inherits publicly from Option<long>). I selected this
approach because I wanted a uniform interface for obtaining the type and
value of a given option. I came up with the following class tree for testing
purposes:
template <typename T>
class Option
{
public:
   enum OptionType
   {
      LONG,
      STRING
   };

   Option(const std::string& name)
      :
      m_name(name),
      m_not_set(true) {}

   virtual ~Option() {}

   T get_value() const
   {
      if(m_not_set)
         throw;

      return m_value;
   }

   void set_value(const T& value)
   {
      m_not_set = false;

      m_value = value;
   }

   virtual OptionType get_type() const = 0;

private:
   std::string m_name;
   bool m_not_set;
   T m_value;
};

class LongOption : public Option<long>
{
public:
   LongOption(const std::string& name)
      :
      Option<long>(name) {}

   virtual OptionType get_type() const
   {
      return STRING;
   }
};

class StringOption : public Option<std::string>
{
public:
   StringOption(const std::string& name)
      :
      Option<std::string>(name) {}

   virtual OptionType get_type() const
   {
      return LONG;
   }
};

That seems to compile, but I cannot do:
std::vector<Option*> options(11);
options[0] = new StringOption("Name=");
The compiler complains:
$ make gccmain
g++ gccmain.cpp -o gccmain
gccmain.cpp: In function `int main()':
gccmain.cpp:6: error: use of class template `template<class T> class Option'
as expression
gccmain.cpp:6: error: parse error before `>' token
gccmain.cpp:8: error: `options' undeclared (first use this function)
gccmain.cpp:8: error: (Each undeclared identifier is reported only once for
   each function it appears in.)
make: *** [gccmain] Error 1

Not being able to store my different options in the same container makes
reading the file with options a lot messier...are their any ways to solve
this? I'm not very good at templates so I've certainly made a number of
silly mistakes.

/ Eric

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