::gets has not been declared

[Marc Glisse]

On Thu, 5 Jan 2012, Marc Glisse wrote:

> Do you have any suggestion on what libstdc++ can do when faced with C 
> libraries that will randomly declare gets or not depending on flags? It would 
> need knowledge of these exact flags so it can provide a replacement exactly 
> when it isn't declared (or at least remove the using ::gets in that case, 
> even if that is non-standard). The easiest workaround I can think of is to 
> implement a failsafe version of using in the front-end, but there might be 
> better solutions.

Maybe a C++03 version of some fancy template game like this?

#ifndef NOGETS
char* gets(char*){std::cout << "from libc\n";return 0;}
#endif

namespace Help1 {
         struct Toobad{};
         Toobad gets(...);
}
namespace Help2 {
         using namespace Help1;
         template<class T> struct A {
         static const bool 
value=std::is_same<decltype(gets(std::declval<T>())),Help1::Toobad>::value 
&& std::is_convertible<T,char*>::value;
         };
}
template<class T> typename std::enable_if<Help2::A<T>::value,char*>::type 
gets(T x){ std::cout << "from libstdc++, call fgets\n";return 0; }


Certainly not completely legal, but might be close enough?

-- 
Marc Glisse