On Sun, Nov 14, 2010 at 08:47:30PM +0100, Hans van der Meer wrote:
> 
> On 14 nov 2010, at 20:27, Khaled Hosny wrote:
> 
> > On Sun, Nov 14, 2010 at 06:55:20PM +0100, Hans van der Meer wrote:
> >> In transforming dates through a Lua-call I get a nil error I do not 
> >> understand.
> >> 
> >> The luatex code =
> >> \startluacode
> >>    hvdm = hvdm or {}
> >>    require "lpeg"
> >> -- Transform date in Lua from yyyymmdd to dd-mm-yyyy with checks
> >>    hvdm.day = lpeg.R("02") * lpeg.R("09") + lpeg.P("30") + lpeg.P("31") - 
> >> lpeg.P("00")
> >>    hvdm.month = lpeg.P("0") * lpeg.R("19") + lpeg.P("10") + lpeg.P("11") + 
> >> lpeg.P("12")
> >>    hvdm.year = lpeg.R("12") * lpeg.R("09") * lpeg.R("09") * lpeg.R("09")
> >>    hvdm.date = lpeg.C(hvdm.year) * lpeg.C(hvdm.month) * lpeg.C(hvdm.day) * 
> >> -1 / "%3-%2-%1"
> >> \stopluacode
> >> \def\FormatDate#1{\ctxlua{tex.print(tostring(hvdm.date:match(#1)))}}
> >> 
> >> Calling \FormatDate(1) is OK although it returns "nil" (correct would be 
> >> #1 = 20101114
> >> Calling \FormatDate(A) is  not OK with the error:
> > 
> > You are passing a undefined variable, A. Your argument should be quoted:
> > 
> >     hvdm.date:match("#1")
> > 
> 
> I would think that is not the case. 
> For one, because then calling with argument 1 would fail in the same manner 
> as argument A does; which does not happen.

No, match(1) will match an integer 1, match("1") matches a string "1",
while match(A) will match a variable A which is not what you are after,
while match("A") will match a string "A".

> Secondly, the call originates from
>   \startxmlsetups xml:case:burned
>     \xmldoifelsetext{#1}{}{\FormatDate{\xmlflush{#1}}}{\currentdate}
>   \stopxmlsetups
> This does makes it a string already.

TeX is not lua, the concepts are completely and totally different.

> Something else must happen here, I guess.

No, there isn't.

Regards,
 Khaled

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer
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