From: Hans Hagen <j.hagen@xs4all.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: Checking existence of a macro (control sequence) by Lua
Date: Thu, 28 May 2020 10:34:34 +0200 [thread overview]
Message-ID: <e3765ad9-34e4-8e24-e0bb-324078a9267b@xs4all.nl> (raw)
In-Reply-To: <b58899c80e0ea1da906ac3a00e427faf@vivaldi.net>
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
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next prev parent reply other threads:[~2020-05-28 8:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 22:42 context
2020-05-27 22:49 ` luigi scarso
2020-05-28 7:56 ` Hans Hagen
2020-05-28 6:50 ` Henri Menke
2020-05-28 8:34 ` Hans Hagen [this message]
2020-05-28 11:24 ` context
2020-05-28 21:24 ` context
2020-05-29 7:36 ` Hans Hagen
2020-05-29 21:21 ` context
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