# Re: [NTG-context] arguments to ctxlua

On 30-3-2010 19:45, Hans van der Meer wrote:

When I have a Lua function with 2 arguments:
\startluacode
function f(a,b)
...
\stopluacode

called through:
\def\callf#1#2{\ctxlua{f("#1","#2")}}

and do this actually with one argument:
\callf{one}



so, #1 will be one and #2 will be the next token (whatever that is)


then I find that the absent argument b in f(a,b) is not nil but a string
of length 1.

That is a bit of a nuisance because I would like to use the Lua idiom:
function f(a,b)
local b = b or default
but that is frustrated by the behaviour shown.

Is this an artifact of either luatex or ConTeXt? Can it be avoided such
that in this case b will be nil?


just tex

but in any case even if #2 is empty you need to test like this

local b = b ~= "" and b or default

watch the order ... we want b to be set to b when not empty

Hans

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