[Boost-users] exception: use of error_info can mask real exceptions

Subject: [Boost-users] exception: use of error_info can mask real exceptions
From: Andrew Venikov (Andrew.Venikov_at_[hidden])
Date: 2009-05-20 17:26:48

Just wanted to ask if there were commonly accepted solutions to the
following problem:

typedef boost::error_info<struct tag_f1, std::string> f1_descr;

and then

throw f1exception() << f1_descr("blah blah blah").

and later

catch(f1exception & ex){...}

The constructor of std::string may throw an exception in which case
f1exception will never be thrown.
This is not necessarily the desired outcome as the intention was
obviously to indicate f1exception error,
not the string() error.

This problem pertains to any type that throws exceptions in its
constructor and is used with error_info idiom.

What may be more appropriate is something like this

typedef boost::error_info<struct tag_f1, shared_pointer<string> >
f1_descr
...
error condition is detected
shared_ptr<string> pErrStr;
try
{
   pErrStr = new string("Error description");
}
catch(bad_alloc & ex)
{
}

throw f1exception() << f1_descr(pErrStr);

Meaning that if string fails to allocate memory, I'm willing to forgo
the 
error description but still throw the intended exception.

Is there a cleaner way to do that?

Thanks,
     Andy.