[Rcpp-devel] Datetime substraction bug ?

[stat quant]

Thanks,
agreed, "bug" can be replaced by "feature" here, though a surprisingly
strange one as I never encountered such in any dateTime class.
Good news is that operator < is implemented as I thought

   - bool operator<<http://dirk.eddelbuettel.com/code/rcpp/html/namespaceRcpp.html#adf2a70049435b345d5d049c3ab00658b>
   (const Datetime<http://dirk.eddelbuettel.com/code/rcpp/html/classRcpp_1_1Datetime.html>&d1,
   const Datetime<http://dirk.eddelbuettel.com/code/rcpp/html/classRcpp_1_1Datetime.html>&
   d2) { return
d1.m_dt<http://dirk.eddelbuettel.com/code/rcpp/html/classRcpp_1_1Datetime.html#a0655024a342ad356a28b3a58d4886956><
d2.
   m_dt<http://dirk.eddelbuettel.com/code/rcpp/html/classRcpp_1_1Datetime.html#a0655024a342ad356a28b3a58d4886956>;
   }

It teaches a lesson: always go and check the sources (unless you are
looking at a commutative operator ;))

2013/3/31 Robin Girard <robin.girard at mines-paristech.fr>

> Actually that's not a big trick
> date.getFractionalTimestamp() returns date.m_dt which is a double. The
> substraction on double is the "usual one" and
> date_end.getFractionalTimestamp()-date_begin.getFractionalTimestamp()
> gives a positive number if and only if date_end>date_begin.
>
> My only regret is that it gives longer code line and less ease of reading.
> But I clearly understand that it's a matter of convention and if other have
> integrated this convention this cannot be changed now, otherwise it will
> become a bug for them...
>
> at the end a "bug" is only a missinterpretation of something somewhere ? :)
>
> lots of .getFractionalTimestamp() everywhere for me ...
> R.
>
>
> ----- Mail original -----
> De: "stat quant" <statquant at outlook.com>
> À: "Robin Girard" <robin.girard at mines-paristech.fr>
> Cc: rcpp-devel at lists.r-forge.r-project.org
> Envoyé: Dimanche 31 Mars 2013 11:32:08
> Objet: Re: [Rcpp-devel] Datetime substraction bug ?
>
> Thanks a lot for reporting this I would surely have been caught (may be I
> am I'll go through code I wrote using this) by this bug.
> Posting your workaround would not hurt I think...
>
> Thanks and cheers
>
>
> 2013/3/30 Robin Girard < robin.girard at mines-paristech.fr >
>
>
> Thanks you're right I already wrote it myself with getFractional...
> and indeed that's not really what we should call a "bug" but it took me a
> while to understand that
>
> if date1-date2>0 then date1<date2 ;)
>
> R.
>
>
> ----- Mail original -----
> De: "Dirk Eddelbuettel" < edd at debian.org >
> À: "Robin Girard" < robin.girard at mines-paristech.fr >
> Cc: rcpp-devel at lists.r-forge.r-project.org
> Envoyé: Samedi 30 Mars 2013 00:44:08
> Objet: Re: [Rcpp-devel] Datetime substraction bug ?
>
>
>
>
> On 29 March 2013 at 23:37, Robin Girard wrote:
> | Hi List
> |
> | why is it that we have in the Datetime definition
> | (here
> http://dirk.eddelbuettel.com/code/rcpp/html/Date_8cpp_source.html#l00271 )
> |
> | double operator-(const Datetime& d1, const Datetime& d2) { return
> d2.m_dt - d1.m_dt; }
> | bool operator<(const Datetime &d1, const Datetime& d2) { return d1.m_dt
> < d2.m_dt; }
> |
> | I feel there is a contradiction
> | substraction shoulb be d1.m_dt - d2.m_dt; no ?
>
> It's been a while since I wrote that and I think I followed the difftime()
> convention in R. Or maybe not. To me d1 comes before d2 in the way the
> arguments are given, so d2 is larger and I want to subtract d1 from d2.
>
> In any event, if it bugs you greatly you are always free to write your own
> function. ;-)
>
> Dirk
>
> |
> | Robin
> |
> | Dr. Girard Robin
> | Chargé de Recherche
> |
> | MINES-ParisTech / Département Energétique et Procédés / PERSEE / Groupe
> ERSEI
> | Centre Procédés, Energies Renouvelables et Systèmes Energétiques (PERSEE)
> | Center for Processes, Renewables Energies and Energy Systems
> | Renewable Energies & Smartgrids (ERSEI)
> |
> | 1 Rue Claude Daunesse - CS 10207 - F-06904 Sophia Antipolis Cedex
> | Tel: +33.4.93.67.89.64 (~99), Fax: +33.4.93.95.75.35
> | e-mail : robin.girard at mines-paristech.fr
> |
> | web page perso http://www.mines-paristech.fr/Services/Annuaire/&?id=8828
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> |
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