Re: [Boost-Users] Problem with boost::any.

From: Douglas Gregor (gregod_at_[hidden])
Date: 2002-10-11 08:34:27

On Friday 11 October 2002 09:05 am, Luc Bergeron wrote:
>    std::string GetStringFromAny(const boost::any& val) const
>    {
>       std::string strVal;
>       try
>       {
>          strVal = boost::any_cast<std::string>(val);
>       }
>       catch(boost::bad_any_cast &err)
>       {
>          std::cerr << err.what() << std::endl;
>          return "";
>       }
>       return strVal;
>    }
>
> But I always have a bad_any_cast exception. From the documentation, at
> leats what I understand of it,  "If passed a value or reference, it
> returns a copy of the value content if successful". Can someone point me
> in the right direction as to how can I extract the value within a
> boost::any type, I think i'm lost !!! :)

This code is correct AFAICT. Are you sure that the boost::any actually has a 
std::string in it? It's a very common mistake to try to test a routine like 
this with:

  GetStringFromAny("foo")

The type of "foo" is const char*, not std::string.

        Doug