Re: [boost] Re: boost::date_time: ISO compliant IO for periods/durations?

From: Jeff Garland (jeff_at_[hidden])
Date: 2004-05-11 13:05:19

On Tue, 11 May 2004 17:45:43 +0200, Daniel Krügler wrote 
 
> OK, I understand the nature of the problem here. And probably it  
> wouldn't help, if ISO 8601 would define a month in this context, 
> would it? Regrettably I have no access to the full 8601 spec, but  
> does anyone have?  
 
I have seen it and it doesn't discuss the semantic issues associated with 
such a representation -- only how it should be formatted as text. 
 
> Lets assume, that ISO 8601 would provide a  
> resolution, would it make sense to make such an iso_... function  
> available (Because it would depend on a special calendar definition)? 
 
I have no problem adding the parsing, but there needs to be something to 
parse to. I have some experimental code that will likely become available in 
the future that represents months and years as a 'logical duration' type 
that is different from the 'physical duration' types.  You can then imagine 
a structure like: 
  struct logical_duration 
  { 
    logical_duration(years y, months m, days d, ...etc...); 
    private:  
     months month_count; //years just convert to months by multiplying by 12 
     time_duration time;  //physical duration of all the other parts 
  }; 
 
Then a duration like this could be parsed into this structure and then would 
provide for the usual interactions with the other classes in the library.  
For example: 
  logical_duration ld = from_iso_string("P18Y9M4DT11H9M8S"); 
  ptime t += add_with_end_of_month_snap(t, ld); 
 
And since none of this is in the library currently, I'd like to hear any 
details of your use case that you can share... 
 
Jeff