Re: why nil argument

[Hans van der Meer <H.vanderMeer@uva.nl>]

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.
Secondly, the call originates from
  \startxmlsetups xml:case:burned
    \xmldoifelsetext{#1}{}{\FormatDate{\xmlflush{#1}}}{\currentdate}
  \stopxmlsetups
This does makes it a string already.
Something else must happen here, I guess.

Hans van der Meer


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