On 05/03/2011 05:22 AM, Tobias Germer wrote:
Hi all,
I think there is a problem with the behavior of boost::as_literal. If I got it right, it is supposed to create an iterator_range from null-terminated strings, which is fine. However, it also creates iterator_ranges from exisiting ranges, i.e., it converts general ranges to iterator_ranges. I think as_literal should fall back to identity (i.e., just return its argument) if its argument is already a range.
With the current behavior, the type information of the range is lost. This is a problem if I write generic code and want to dispatch several cases based on the type of the range. Consider the following example:
------------------------------- template<class Rng> void f( Rng const& r ) {...} template<class T> void f( iterator_range<T*> const& r ) {...} void f( std::string const& s ) {...} void f( std::vector const& v ) {...}
template<class Rng> void g( Rng const& r ) { f(as_literal(r)); ... }
-------------------------------
Function g() accepts general ranges as well as zero-terminated strings. It dispatches its argument using the type of the range and the overloads of f(), in order to execute special code for some ranges like strings and vectors. (In my particular case, I have special treatment for ranges of contiguous memory.)
Note that at least in your case, it seems there should be a more direct way to achieve what you want, e.g. an iterator/range trait to determine if an iterator can be handled like a pointer to contiguous memory.