Re: std::map lookup function
Unfortunately, this returns a reference to a part of the local object
"it", so this won't work.
What is the solution?
Very good question.
I can't think of a satisfactory method off-hand. Ofcourse, you could
dynamically allocate the object and return an "auto_ptr"... but that would
be a last resort. Maybe a macro is justified? (Yes I know they're evil)
(I couldn't actually get this to work without having use of the "typeof"
operator, but nonetheless here's my feeble attempt:)
#include <map>
struct Lookup_Error {};
template <class T>
class GetType
{
public:
GetType(T& object);
typedef T Type;
};
#define lookup(m,v) ( ( GetType(m)::Type::iterator it_local999 = m.find,\
if ( it_local999 == m.end() ) throw Lookup_Error(); )
\
, it_local999 )
int main()
{
std::map<int,char> my_map;
std::map<int,char>::iterator &it = lookup(my_map, 4);
//"it" is in scope until end of main
}
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