>From: "David Abrahams" <[EMAIL PROTECTED]>
> Terje Slettebų <[EMAIL PROTECTED]> writes:
>
> >> C:\Program Files\Boost\boost_1_30_0\boost/lexical_cast.hpp(74) :
warning
> > C4512: 'no_lexical_conversion<class std::basic_string<char,struct
> > std::char_traits<char>,class std::allocator<char> >,long>' : assignment
> > operator could not be generated
> >
> > This is due to that it stores a const std::string object, describing the
> > exception
>
> Are you saying that you have defined an exception with a std::string
> member? That's VERY bad! Throwing that exception can lead directly
> to termination!
You mean if the exception itself throws during construction or copying?
I've tried the program below on Intel C++ 7.0 and MSVC 6, and I haven't got
it to call terminate(). It may be that it doesn't handle exceptions
correctly, though.
#include <iostream>
#include <string>
#include <stdexcept>
class Exception : public std::runtime_error
{
public:
Exception() : std::runtime_error("Exception")
{ throw std::runtime_error("Construction"); }
Exception(const Exception &) : std::runtime_error("Exception (copied)")
{ throw std::runtime_error("Copy"); }
};
int main()
{
try
{
throw Exception();
}
catch(const std::exception &e)
{
std::cout << "Exception - " << e.what() << '\n';
}
catch(...)
{
std::cout << "Unknown exception\n";
}
}
As it stands, it prints "Exception - Constructor", as it throws an exception
in the constructor of the Exception exception. If the throw-statement in the
constructor is commented out, it prints "Exception - Exception", apparently
not invoking the copy constructor when throwing the exception (which it's
allowed to).
> What's wrong with char const*?
You mean storing the string as a character array? Sure, that's possible, and
I see that STLPort do it, and it's probably safer, as you say. It does mean
you have to specify the maximum string length in advance, though. As
"no_lexical_conversion" what() prints out the source and target types, it
may truncate long type names.
Regards,
Terje
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