Re: buffer question

On Thu, Apr 16, 2026 at 11:46 (-0400), Aditya Mahajan wrote:

> On Thu, 16 Apr 2026, Jim via ntg-context wrote:

>> Aditya presciently anticipated (is that redundant?) Question 3 of
>> International Buffer Day, which was going to be

>> Q3: How to create a buffer from inside a macro?

>> Given Aditya's answer to Q2, the solution is pretty simple:

>> \def\makeMyPreamble #1
>> {
>>     \startluacode
>> local preamble3 = [[
>>             \definepapersize[ShowAndTypeset]
>>                             [width=100mm, height=#1]
>>             \setuppapersize[ShowAndTypeset]
>>         ]]
>> context.tobuffer("MyPreamble", preamble3)
>>     \stopluacode
>> }

> This is a bit risky with catcodes.

Good point!  (In general... in this specific case, I would imagine that any
simple dimen will not have catcode issues.  But as I type this I have this
feeling someone might educate me on that point.)

> (Quiz: is % inside \startluacode a tex comment or not?)

When I first tried to put your
        %width%
construction into the macro I quickly found out the catcodes issue was a
bit of an issue.

> Better to define a function, say thirddata.definepreamble(width,height)
> at lua end and then call

> \define[1]\makePreamble{\ctxlua(thirddata.definepreamble("#1","100cm")}

Without having done my Lua programming yet, am I correct in assuming that
if someone calls this \makePreamble as follows
        \makePreamble{0.5"}
then Bad Things will happen because of the " in the argument?

                                Jim
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