[Rcpp-devel] Datetime substraction bug ?

[Romain Francois]

Le 02/04/13 17:57, Dirk Eddelbuettel a écrit :
>
> I agree with everybody too :)
>
> I still like my example, and I obviously respect operator- "in general".
>
> What I can't square is whether the code for operator- (which I may in fact
> have defined the way I like it) _actually gets called_.

Of course it is called.

If I switch your code to

int   operator-(const Date& d1, const Date& d2) {
         Rprintf( "d1 = %d\n", d1.m_d ) ;
         Rprintf( "d2 = %d\n", d2.m_d ) ;
         int diff =  d2.m_d - d1.m_d;
         Rprintf( "diff = %d\n", diff );
         return diff ;
     }

or similar in class Datetime.

 > NewYear <- as.Date("2013-01-01")

 > Easter <- Sys.Date()

 > cppFunction('double ddiff(Date a, Date b) { return a - b; }')

 > cppFunction('double ddiff2(Date a, Date b) { return b - a; }')

 > ddiff(NewYear, Easter)
d1 = 1606400880
d2 = 1606389816
diff = 91
[1] 91

 > ddiff2(NewYear, Easter)
d1 = 1606400944
d2 = 1606389816
diff = -91
[1] -91

This is getting ridiculous.


> In what I sent on March 31 as the NewYear/Easter example:
>
>    R> NewYear <- as.Date("2013-01-01")
>    R> Easter <- Sys.Date()
>    R> cppFunction('double ddiff(Date a, Date b) { return a - b; }')
>    R> cppFunction('double ddiff2(Date a, Date b) { return b - a; }')
>    R> ddiff(NewYear, Easter)
>    [1] 89                            ## I find this more logical
>    R> ddiff2(NewYear, Easter)
>    [1] -89                           ## closer to R's difftime and 'odd' to me
>    R>
>
> If it isn't used here, where is it actually used?
>
> Dirk
>


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Romain Francois
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