Re: Checking existence of a macro (control sequence) by Lua - problem after updating MkIV

["Lukas/ConTeXt" <lpr.context@email.cz>]

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Hello,




I need to check within Lua.

My sample cases are very minimalistic - I'm working on more complicated task
actually, where check-for-control-sequence-existence need to be performed 
run-time within Lua scope.




Best,




Lukas



---------- Původní e-mail ----------
Od: Hans van der Meer <havdmeer@ziggo.nl>
Komu: NTG ConTeXt <ntg-context@ntg.nl>
Datum: 18. 6. 2020 12:25:42
Předmět: Re: [NTG-context] Checking existence of a macro (control sequence)
by Lua - problem after updating MkIV
"
Why can you not simply use one of the doifundefined macro's? Something for
example:


\doifundefined{ExitStatus}{\gdef\ExitStatus{0}} % default to ok as in UNIX




dr. Hans van der Meer









"
On 18 Jun 2020, at 10:27, Lukas/ConTeXt <lpr.context@email.cz
(mailto:lpr.context@email.cz)> wrote:



Hello,
I'm using Hans' macro suggested some time before.
I've just updated Ctx MkIV and my sample code:

----
\starttext
 \def\MyMacro{Ahoj}

  \def\MyMacWithPars#1#2{Something}

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

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

  \startluacode
    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

    --

    local defined = tokens.defined

   for _, v in ipairs{ "MyMacro", "MyMacWithPars", "Undefined", "DoNothing",
"NonExisting" } do
     print(string.format("\letterpercent-12s", v), defined(v), defined(v,
true), defined(v, false))
   end
  \stopluacode

  Aaa
\stoptext
----

gives:
"
MyMacro         false   false   false
MyMacWithPars   false   false   false
Undefined       false   false   false
DoNothing       false   false   false
NonExisting     false   false   false
"

IOW, I'm not able to determine whether a control sequence has not been
defined (or has \undefined value) or not.

Am I doing a trivial mistake or has anything changed?

Thank you for patience...

Lukas<IsMacDef3.log><IsMacDef3.mkiv><IsMacDef3.log_>________________________
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