Re: [Boost-users] date_time:

25 Oct 2005

      I will post test code for date & variant performance.

-----Original Message-----
From: boost-users-bounces@lists.boost.org
[mailto:boost-users-bounces@lists.boost.org] On Behalf Of Jeff Garland
Sent: Monday, October 24, 2005 8:35 AM
To: boost-users@lists.boost.org
Subject: Re: [Boost-users] date_time:

On Mon, 24 Oct 2005 07:08:49 -0400, Piyush Kapadia wrote
...
I too tested boost date and found that it is extremely slow and eventually
had to write code that performs much faster.
For parsing only, or for other purposes? Your general statement isn't
precise
enough to be of help. Slowness in the parsing isn't a new report -- there
are
certainly a series of changes that would make the to_string routines faster.

Some of them have been submitted over time and have been incorporated.  Some
that have been submitted incorporate statics and other techniques that might
compromise the correctness of the library in some environments and hence
don't
get added.  Submissions are always welcome.
...
Speed is one of major strength of C++, we should produce performance 
details of each module as well.
If you really want to help, perhaps you should consider becoming the Boost
"performance wizard" -- it would be a tremendous amount of work.
...
For example boost::variant is 20 times slower than boost::any, which 
are similar in functionality, boost::any is very easy to use and is 
very fast but does not support serialization.
For what operation?  There may be good reason why variant must be slower.
...
-----Original Message-----
From: boost-users-bounces@lists.boost.org
[mailto:boost-users-bounces@lists.boost.org] On Behalf Of __PPS__
Sent: Monday, October 24, 2005 2:18 AM
To: boost-users@lists.boost.org
Subject: [Boost-users] date_time:
Are there better conversion functions from ISO date format (calendar,
 ordinal, week dates) in basic and/or extended format? Should 
conversion from invalid iso date like "20050231" fail or produce 
same results as date(2005,02,31). (I know that it produces the same 
results, but is it right to convert invalid iso date representation 
to valid date?)
In 1.33 the following code produces 2 exceptions:

  try {
    std::string ds("20050231");
    date d = from_undelimited_string(ds);
    std::cout << d << std::endl;
  }
  catch(bad_day_of_month& e) {
    std::cout << "exception: " << e.what() << std::endl;
  }

  try {
    date d(2005,02,31);
    std::cout << d << std::endl;
  }
  catch(bad_day_of_month& e) {
    std::cout << "exception: " << e.what() << std::endl;
  }
...
Another thing I noted, some conversion functions accept const 
std::string &, but most of them accept plain std::string, isn't 
better to convert all of them to constant references???
Sure unless they copy the string anyway, which I don't think they do.
...
If anybody interested, I wrote such function that accepts iso date 
string in any of the above mentioned 6 combinations and returns 
date. It runs 90-100 times faster than equivalent 
date_from_iso_string from boost. And yes, it does make sure that 
"20050229" fails
As I said above, contributions always welcome.

Jeff
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