[REBOL] Re: R: Re: [REBOL]
From: riusa:email:it at: 1-Feb-2002 8:57
Using triples is a good idea! thanks for other suggestions!
> Hi, Alessandro,
>
> I suggest using strings instead of words. Strings always evaluate
> to themselves, while some expressions could end up trying to take
> the value of MAR or GIU with unexpected results! ;-)
>
> Alessandro Manotti wrote:
> >
> > month-list: [gen jan feb feb mar mar apr apr mag may giu jun lug
> > jul ago aug set sep ott oct nov nov dic dec]
> >
> > select month-list 'feb
> > select month-list 'giu
> >
> > Of course, it is good only for ITALIAN->ENGLISH (for reverse, we
> > should reverse the order of the items...).
> >
>
> You can avoid having two lists by using triples instead of pairs,
> as follows:
>
> translate-month: func [month-name [string!]] [
> select [
> "gen" "jan" "gen" "feb" "feb" "feb" "mar" "mar" "mar"
> "apr" "apr" "apr" "mag" "may" "mag" "giu" "jun" "giu"
> "lug" "jul" "lug" "ago" "aug" "ago" "set" "sep" "sep"
> "ott" "oct" "ott" "nov" "nov" "nov" "dic" "dec" "dic"
> ] month-name
> ]
>
> which works as
>
> >> translate-month "jan" == "gen"
> >> translate-month "lug" == "jul"
> >> translate-month "ott" == "oct"
> >> translate-month "oct" == "ott"
>
> >
> > date1: [gen feb mar apr mag giu lug ago set ott nov dic]
> > date2: [jan feb mar apr may jun jul aug sep oct nov dec]
> >
> > idx: index? find date1 'gen
> > date2/:idx
> >
> > * Advantage: reverse is ok...
> >
> > idx: index? find date2 'gen
> > date1/:idx
> >
>
> A drawback of using ... INDEX? FIND ... is the behavior when an
> invalid argument is supplied. Packaged up as a function, with a
> refinement to control the direction of translation, we can use the
> above idea as:
>
> trans-mon: func [mon-name [string!] /to-it /local date-it date-en] [
> date-it: [
> "gen" "feb" "mar" "apr" "mag" "giu"
> "lug" "ago" "set" "ott" "nov" "dic"
> ]
> date-en: [
> "jan" "feb" "mar" "apr" "may" "jun"
> "jul" "aug" "sep" "oct" "nov" "dec"
> ]
>
> either to-it [
> pick date-it index? find date-en mon-name
> ][
> pick date-en index? find date-it mon-name
> ]
> ]
>
> which behaves this way:
>
> >> trans-mon "gen" == "jan"
> >> trans-mon "ott" == "oct"
> >> trans-mon/to-it "oct" == "ott"
> >> trans-mon/to-it "may" == "mag"
>
> ... but ...
>
> >> trans-mon "abc"
> ** Script Error: index? expected series argument of type: series
port
> ** Where: trans-mon
> ** Near: pick date-en index? find date-it
>
> So, regardless of the strategy chosen, handling erroneous cases should
> be part of the plan, IMHO.
>
> -jn-
> --
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