Re: [boost] [serialization]Serialisation/deserialisationoffloating-point values

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2006-05-03 04:13:30

|  -----Original Message-----
|  From: boost-bounces_at_[hidden] 
|  [mailto:boost-bounces_at_[hidden]] On Behalf Of Robert Ramey
|  Sent: 02 May 2006 19:33
|  To: boost_at_[hidden]
|  Subject: Re: 
|  [boost][serialization]Serialisation/deserialisationoffloating
|  -point values
|  
|  Could we consider removing the word "serialization" from 
|  this subject here?  This is really about rendering floating 
|  point numbers between binary and decimal representations.  

OK - we are veering OT - but it started with a serialization problem and I
thought a new item would confuse the thread.  I think we have reached the
end of the road and await the next Microsoft release.  I will start of new
thread if I have anything more to report.

Meanwhile, if you want to serialize doubles on MSVC, I suggest considering
using << setprecision(17) << scientific.
  
|  Also, a real contribution could be made to address the 
|  variety of NaN's and how they should be rendered in 
|  different systems. This is currently undefined and will 
|  create problems porting data between programs compiled with 
|  diferent compilers and/or libraries.

Jeff Garland made a suggestion:

"The types in date_time have the ability to serialize and deserialize NADT
(not a date time), -infinity and +infinity.  Why couldn't there be a simple
extension to the numpunct<charT> facet to define an appropriate output
string?  Basically something like:

  //see Langer and Kreft p 414...
  template<class charT>
  class numpunct : public locale::facet {
  
    //new functions for nan and infinity
    string_type not_a_number_name() const;  
    string_type infinity_name()     const;  

And you'd have to fix num_get as well."

but it's not something I have time or skill or inclination to tackle. SoC?

Or switch at least NaNs and Infs to a hex format as sketched by John
Maddock?

Or get WG21 to agree a Standard representation for NaNs and Infs instead of
everyone doing their own thing?

Paul

---
Paul A Bristow
Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB
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