On 5/28/2020 12:42 AM, cont...@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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