David Abrahams wrote:
"Beman Dawes" <bdawes@acm.org> writes:
* Boost Lexical Cast has been tentatively accepted by the LWG for TR2.
Was there any discussion of the to_string(x) and string_to<T>(x) alternative?
That would be better than the current lexical_cast, provided that there are also basic_string and wstring vresions, i.e.: to_basic_string< CharT, CharTraits, Allocator >( x ) to_wstring(x) The string_to<T> function could have basic_string and wstring overloads, but this would be inconsistent with the rest of the C++ library. As has been mentioned, the to_string methods will not fail conversion. However, it is unclear what to do with string_to that may fail. There are two possible interfaces: 1. throw an exception on failure, like is currently done with lexical_cast 2. provide a boolean or enumeration for failure type (not-EOS, read-fail, etc.) For the second interface, it has been suggested to use something like: bool string_to<T>(x, ret) where ret is an output reference. However, this doesn't allow for the simple one-line interface that lexical_cast provides. Drawing influence from Python, I suggest that the non-throwing version look like: std::pair<T,bool> string_to<T>(x) allowing: fn( string_to<Object>(object).first );
I only ask because I remember the issue coming up somewhere before, and I have never seen a use for lexical_cast that didn't have a string on one end.
Yes. Java, Python and other languages have conversion to strings built in to their framework so classes can provide their own mechanism for converting to a string. In C++, the generic case is 3 lines: std::ostringstream ss; ss << object; fn( ss.str()); compared to the single line above. - Reece _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/