[boost] [date_time]Streaming bugs

From: Martin (adrianm_at_[hidden])
Date: 2005-06-23 08:06:30

1. The date_time library in the currenct CVS doesn't follow the standard 
formatted input/output requirements in the C++ standard.

e.g.

stringstream s("205-Jan-01");
date d;
s >> d;

will throw "Year out of valid range" exception instead of just setting the 
badbit.

The resolution is to use the sentry object and catch exceptions:

template <class charT, class traits>
inline std::basic_istream<charT, traits>&
operator>>(std::basic_istream<charT, traits>& is, date& d) {
  std::basic_istream<charT, traits>::sentry cerberos(is, false); 
  if (cerberos) {
    std::ios_base::iostate status = std::ios_base::iostate
(std::ios_base::goodbit);
    try {
      ... //use facet and set status if failed
    }
    catch (...) {
      is.setstate(std::ios_base::badbit);
    }
    if (status)
      is.setstate(status);
  }
  return is
}

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2. The default date format is "%Y-%b-%d" which is very confusing since it is 
using a date order that is not common in english speaking countries while it 
uses english month names.
The default format should be "%x".
(I know this will create problems with input parsing on some STL libraries but 
I think it is a better than the current solution where almost nobody can use 
the default).

---------------
3. The streaming functions all add a new facet to the locale if no current 
facet has been imbued. Wouldn't it be better to either have a 
singleton "default" facet for all streams or imbue the facet to the global 
locale instead?