On 10/16/2021 10:33 AM, Wolfgang Schuster via ntg-context wrote:
Ramkumar KB via ntg-context schrieb am 16.10.2021 um 06:00:
Hello All,
I was trying to read the value of '\totalnumberofpages' into lua to do
something with it. As an example, see below.
Now, as I understand it, my example would not work as TeX gets the
first go at this and therefore the variable 'pages' is the string
'\totalnumberofpages' and not the actual value itself. And Lua cannot
process this "calculation".
I tried to go thru the manual - *cld-mkiv.pdf *- in the distro but
could not catch on how to read a metadata value (not print). I am sure
that I am missing a small trick somewhere (or is it something more
involved?).
\startluacode
function myFancyCalculations(pages)
-- some fancy stuff but as an example
local myCal = tonumber(pages) + 1
return myCal
\stopluacode
\starttext
\blah
\ctxlua{context(myFancyCalculations("\\totalnumberofpages"))}
\stoptext
Everything gets easier when you use the Lua functions to access the
counter values but be aware the values can be wrong when you're at a
page break.
\startbuffer[pagenumber]
\startluacode
context.starttabulate()
context.NC()
context("Current page")
context.EQ()
context(structures.counters.get("realpage",1,"number"))
context.NC()
context.NR()
context.NC()
context("Last page")
context.EQ()
context(structures.counters.get("realpage",1,"last"))
context.NC()
context.NR()
context.stoptabulate()
\stopluacode
\stopbuffer
\starttext
\dorecurse
{\randomnumber{5}{10}}
{\getbuffer[pagenumber]
\page}
\stoptext
As addendum ... The problem in general with macros is that one doesn't
really knows by looking at the name what actually happens when it
expands, which can be a lot. Now, because \totalnumberofpages is
supposed to 'return' a number and not typeset something styled (which
itself involved macro expansion) you can actually do this:
\startluacode
local n = tokens.getters.macro("totalnumberofpages",true)
print(">>>",type(n),n)
\stopluacode
but beware of the fact that you actually get back a string:
\startluacode
local n = tokens.getters.macro("totalnumberofpages",true)
print(">>>",type(n),n)
local n = tonumber(n)
print(">>>",type(n),n)
\stopluacode
etc etc
Hans
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