On 6/10/2024 7:08 AM, Max Chernoff wrote:

Hi Hraban,

On Sun, 2024-06-09 at 22:12 +0200, Henning Hraban Ramm wrote:

...

when I define a measure on the TeX side, I used to get at the value in Lua with tex.getdim, like:

\definemeasure[Bleed][3mm]

tex.getdimen("Bleed")

But now I get "incorrect dimen name". I need it as a dimension, since I do calculations with other dimensions like "topspace".

How should I do this correctly?

There doesn't appear to be any official interfaces to get the value of a measure from Lua, but the following should work okay:

 \definemeasure[mymeasure][10pt]

 \newdimen\mydimen \mydimen=10pt

 \definemeasure[measureexpr][1in + 27.73pt]

 \startluacode
     -- Returns the unexpanded value of some variable in a namespace.
     local function get_variable(namespace, variable)
         -- -- Doesn't work since "measure" is defined as a "system namespace".
         -- namespace = interfaces.getnamespace(namespace)
         namespace = tokens.getters.macro("??" .. namespace)
         return tokens.getters.macro(namespace .. variable)
     end

     -- Gets the value of a measure and converts it to an integer in sp units.
     local function get_measure(name)
         return tex.sp(get_variable("measure", name))
     end

     -- Gets the \dimexpr-evaluated value of a measure, in sp units.
     local function get_measure_expr(name)
         local namespace = tokens.getters.macro("??measure")
         -- Undocumented, but seems to work as expected.
         return tex.getdimensionvalue(namespace .. name)
     end

     -- Print the values of the lengths.
     print(("="):rep(80))
     print("mymeasure:"  , get_measure("mymeasure")       )
     print("mydimen:"    , tex.dimen["mydimen"]           )
     print("measureexpr:", get_measure_expr("measureexpr"))
     print(("="):rep(80))
 \stopluacode

 \startTEXpage
     \measure{mymeasure}
     \the\mydimen
     \measure{measureexpr}
 \stopTEXpage

Thanks, -- Max

Indeed we can have:

local namespace = tokens.getters.macro("??measure")

function tex.getmeasure(name,asdimen) local value = tex.getdimensionvalue(namespace..name) if asdimen then return value .. "sp" else return value end

and when you want to avoid the namespace you can do:

function tex.getmeasure(name,asdimen) local value = token.getexpansion("\tointeger\measured{"..name.."}") if asdimen then return value .. "sp" else return tonumber(value) end end

which is some 4 times slower. It'sindeed not documented (although there are some examples in accessors-001.tex) but it's in one of my todo's because I can use it in some places (there ar emopre such todo's) after which it will be discussed in one of the lowlelvel manuals

i'll add tex.getmeasure to the core (but a bit different)

Hans

----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------

Am 10.06.24 um 10:58 schrieb Henning Hraban Ramm:

...

local namespace = tokens.getters.macro("??measure")

function tex.getmeasure(name,asdimen)          local value = tex.getdimensionvalue(namespace..name)          if asdimen then              return value .. "sp"          else              return value          end

So I needed just tex.getdimensionvalue(namespace..name)

Not to be misunderstood, I couldn’t check yet, maybe I wasn’t clear:

I need to process the measure as a dimension, like \measured{Bleed}.

As far as I tried, neither tex.measured nor context.measured worked (but I wouldn’t swear on it, maybe I had a different error).

I understand now that a dimension in Lua is just a string.

I also messed a few thing up when I converted my macros from measure-macros to measures.

Now my image calculations work again. Phew!

Thank you, Hraban