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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