Hi,
OK, if you try to explicitly make them generic, you are told that they
are implicitly already generic:
> setGeneric("is.finite", function(from, ...) standardGeneric("is.finite"))
Error in setGeneric("is.finite", function(from, ...)
standardGeneric("is.finite")) :
"is.finite" is a primitive function; methods can be defined, but
the generic function is implicit, and can't be changed.
If you query about its genericness before you define you own generic,
you get:
> isGeneric("is.finite")
[1] FALSE
But after you define you own generic, you get:
> setMethod("is.finite", signature(x="TS"),
+ function(x) {
+ Data(x) = callNextMethod()
+ x
+ })
[1] "is.finite"
> isGeneric("is.finite")
[1] TRUE
This all makes some sense, but I am not familiar enough with he
internals to explain exactly why it is done this way. I think you will
fine that 'is.nan' behave exactly the same way.
Thanks,
Lars
Prof Brian Ripley wrote:
> These functions are not generic according to the help page.
> The same page says explicitly that is.nan is generic.
>
> Where did you get the (false) idea that they were generic?
>
> On Thu, 16 Jun 2005 [EMAIL PROTECTED] wrote:
>
>> Full_Name: Lars Hansen
>> Version: 2.1.0
>> OS: SunOS 5.8
>> Submission from: (NULL) (207.66.36.189)
>>
>>
>> Hi,
>>
>> S4 method displacth does not work for the two generic functions
>> 'is.finite' and 'is.infinite'. It turns out that the C functions
>> 'do_isfinite' and 'do_isinfinite' in src/main/coerce.c are missing a
>> call to 'DispatchOrEval' (see do_isnan). Added in the call fixed the
>> problem. My functions no look like this:
>>
>> Form coerce.c:
>>
>> SEXP do_isfinite(SEXP call, SEXP op, SEXP args, SEXP rho)
>> {
>> SEXP ans, x, names, dims;
>> int i, n;
>>
>> if (DispatchOrEval(call, op, "is.finite", args, rho, &ans, 1, 1))
>> return(ans);
>>
>> checkArity(op, args);
>> ...
>>
>> SEXP do_isinfinite(SEXP call, SEXP op, SEXP args, SEXP rho)
>> {
>> SEXP ans, x, names, dims;
>> double xr, xi;
>> int i, n;
>>
>> if (DispatchOrEval(call, op, "is.infinite", args, rho, &ans, 1, 1))
>> return(ans);
>>
>> checkArity(op, args);
>> ...
>
>
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