Re: Exception base class

From:

eca <enrico.ecamail@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Thu, 11 Mar 2010 13:54:14 CST

Message-ID:

<a50bd9ec-ec0a-4e4f-acd7-dc705a633b47@g19g2000yqe.googlegroups.com>

On Mar 10, 4:46 pm, Lars Schouw <schou...@yahoo.com> wrote:

Hi,

I want to construct an exception base class that is easy to use.
Ideally I want to be able to throw exceptions in one liners like this:
throw Exception("string1" + "string2 <number>", 5.0);

I use this:

   class error : public std::exception
   {
   public:
     error() {}
     explicit error(const std::string& arg) : my_str(arg) {}
     virtual ~error() throw() {}

   public:
     virtual const char* what() const throw()
     { return my_str.c_str(); }

     virtual const char * type() const
     { return typeid(*this).name(); }

     template <typename T>
     error& operator<<(const T& v)
     {
       std::ostringstream oss;
       oss << my_str << v;
       my_str = oss.str();
       return *this;
     }

   private:
     std::string my_str;
   };

For debugging purposes, I use to do the following:

void doIt()
{
   double x = 0.0;
   throw error(__FUNCTION__) << " - The value of x is " << x;
}

You can also derive more specialized classes from this and
possibly take advantage of type(), if needed.

HTH,
eca

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