Hello, thanks Henri and Hans for all solutions! On 2020-05-28 10:34, Hans Hagen wrote:

On 5/28/2020 12:42 AM, context@vivaldi.net wrote:

...

Hello,

is it possible to check whether a macro exists (or - is it a non-\undefined control sequence) with Lua? Suppose:

---- \starttext   \def\MyMacro{Ahoj}   \def\MyMac#1#2{Something}

  \startluacode     IsDefined = function(ctl_seq)       print("CS " .. ctl_seq ..                                 (tex.IsCS(ctl_seq) -- Or what to come here?                                                    "is defined" or "is unknown") .. ".")     end

    -- So the function should print to the console:

    IsDefined("MyMacro") --> "CS MyMacro is defined."     IsDefined("MyMac") --> "CS MyMac is defined."     IsDefined("bf") --> "CS bf is defined."     IsDefined("dummy") --> "CS dummy is unknown."

  \stopluacode \stoptext ----

Is it possible? A lot is possible. Take this:

\def\MyMacroA{Ahoj A} \unexpanded\def\MyMacroB{Ahoj B} \frozen \def\MyMacroC{Ahoj C} % in lmtx % \def\MyMacroC{Ahoj C} % barks

At the tex end you can check for several properties:

\ifusercmd \hbox Y\else N\fi % in lmtx \iffrozen \hbox Y\else N\fi % in lmtx \ifusercmd \MyMacroA Y\else N\fi % in lmtx \iffrozen \MyMacroA Y\else N\fi % in lmtx \iffrozen \MyMacroC Y\else N\fi % in lmtx

At the Lua end you can check for being defined:

\startluacode local function whatever(s) context.type("\\" .. s) context(" is %s", tokens.defined(s) and "defined" or "undefined") context.par() end whatever("MyMacroA") whatever("MyMacroD") whatever(" ") whatever("-") \stopluacode

alternatively you can say:

\startluacode local t = token.create("MyMacro") print(t.cmdname == "undefined_cs") \stopluacode

which is less efficient unless you want to access more properties.

Hans

(@Hans: I'm using vivaldi's mail account in "good will" - I didn't suppose it would cause any unwanted actions, like resending mails or whatever.) Bets regards, Lukas

On 5/28/2020 11:24 PM, context@vivaldi.net wrote:

Hello,

one more question - why macros \Undefined and \DoNothing show "defined" although I (tried to) undefine them?

---- \starttext   \def\MyMacro{Ahoj}   \def\MyMac#1#2{Something}

  \def\Undefined{}   \let\Undefined\undefined

  \def\DoNothing{}   \let\DoNothing\donothing

  \startluacode     local str = { [true] = "defined", [false] = "undefined" }

    local function whatever(s)       context.type("\\" .. s)       context(" is " .. (tokens.defined(s) and "defined" or "undefined")) --% Hans' way       context(" and is " .. str[token.is_defined(s)] .. ".") --% Henri's way       context.par()     end

    whatever("MyMacro")     whatever("MyMacroD")     whatever(" ")     whatever("-")     whatever("Undefined")     whatever("DoNothing")   \stopluacode

  %\Undefined % Causes "! Undefined control sequence" \stoptext ----

Gives:

" \MyMacro is defined and is defined. \MyMacroD is undefined and is undefined. \ is defined and is defined. \- is defined and is defined. \Undefined is defined and is defined. \DoNothing is defined and is defined. " Because the macro actually *is* defined: as soon as tex sees

\foo it reserves the name and gives it the meaning undefined, so even \undefined is defined. Anyway, that is why we have \ifdefined that does a different kind of checking. In retrospect, that is a better one, so I'll adapt that in lmtx. \starttext \let\MyMacroA\undefined \startluacode local function whatever(s) context.type("\\" .. s) context(" is " .. (tokens.defined(s,true) and "defined" or "undefined")) --% Hans' way context(" and has meaning " .. (tokens.defined(s) and "defined" or "undefined")) --% Hans' way context.par() end whatever("MyMacroA") whatever("MyMacroB") \stopluacode \stoptext \MyMacroA is defined and has meaning undefined \MyMacroB is undefined and has meaning undefined You can do this in current luatex/mkiv: if CONTEXTLMTXMODE == 0 then local d = tokens.defined local c = tokens.create function tokens.defined(s,b) if b then return d(s) else return c(s).cmd_name == "undefined_cmd" end end end 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 -----------------------------------------------------------------