Checking existence of a macro (control sequence) by Lua

Checking existence of a macro (control sequence) by Lua

[context]

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?

Best regards,

Lukas
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Re: Checking existence of a macro (control sequence) by Lua

[luigi scarso]

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On Thu, May 28, 2020 at 12:43 AM <context@vivaldi.net> wrote:

> Off-topic:
your email are always marked as spam by my gmail . Are you sure that your
address setup is ok  ?

-- 
luigi

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Re: Checking existence of a macro (control sequence) by Lua

[Hans Hagen]

On 5/28/2020 12:49 AM, luigi scarso wrote:
> 
> 
> On Thu, May 28, 2020 at 12:43 AM <context@vivaldi.net 
> <mailto:context@vivaldi.net>> wrote:
> 
> Off-topic:
> your email are always marked as spam by my gmail . Are you sure that 
> your address setup is ok  ?
also, a reply to that vivaldi address always bounces (same for gmx 
accounts, so don't expect answers to those adresses)

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
-----------------------------------------------------------------
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Re: Checking existence of a macro (control sequence) by Lua

[Henri Menke]

On 28/05/20, 00:42, 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?

Yes, that is what the token library is there for.

\starttext

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

\startluacode
local str = { [true] = "defined", [false] = "undefined" }
for _, macro in ipairs({ "MyMacro", "MyMac", "bf", "dummy" }) do
    context(macro .. " is " .. str[token.is_defined(macro)] .. "\\par")
end
\stopluacode

\stoptext

Cheers, Henri

> 
> Best regards,
> 
> Lukas
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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> archive  : https://bitbucket.org/phg/context-mirror/commits/
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> ___________________________________________________________________________________
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Re: Checking existence of a macro (control sequence) by Lua

[Hans Hagen]

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

Re: Checking existence of a macro (control sequence) by Lua

[context]

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
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Re: Checking existence of a macro (control sequence) by Lua

[context]

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.
"

Lukas
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Re: Checking existence of a macro (control sequence) by Lua

[Hans Hagen]

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
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: Checking existence of a macro (control sequence) by Lua

[context]

Hello Hans,

thank you for explanation and the nice how-to solution!

Best regards,

Lukas


> 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
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