Re: [NTG-context] protected macro vs protected luacall

27 Jan 2023


      On Fri, 2023-01-27 at 10:30 +0100, Hans Hagen via ntg-context wrote:
...
On 1/27/2023 10:13 AM, Henri Menke via ntg-context wrote:
...
On Thu, 2023-01-26 at 23:07 +0100, Hans Hagen via ntg-context
wrote:
...
On 1/26/2023 9:33 PM, Henri Menke via ntg-context wrote:
...
\directlua{
    userdata = userdata or {}
    function userdata.test()
      tex.print("\string\\numexpr 17\string\\relax")
    end
}
\tt
\protected\def\test{\directlua{userdata.test()}}
\meaning\test\par
\edef\x{\test}\meaning\x\par
\the\test
\directlua{
    local t = lua.get_functions_table()
    t[\string#t + 1] = userdata.test
    token.set_lua("test", userdata.test, \string#t,
"protected")
}
\meaning\test\par
\edef\x{\test}\meaning\x\par
\the\test
from the code it looks like we're talking plain luatex ...
\the is very selective and doesn't work for all primitives or
macros
compare it to \number which accepts any number representation
following
it while \the doesn't work ok 123
that said, your set_lua is wrong and passes a function as well as
an
index
\directlua{
     lua.get_functions_table()[999] = function()
       tex.print("\string\\numexpr 17\string\\relax")
     end
     token.set_lua("test", 999)
}
\the    \test % needs the \numexpr
\number \test % doesn't
\count0 \test % needs the \numexpr
\count0=\test % doesn't
etc
Thanks for pointing out my mistake. Your example works fine but now
the
luacall is no longer protected and will therefore fully expand in
\edef. So do I understand this correctly that there is no way to
make
the second \the\test work?
\directlua{
     lua.get_functions_table()[999] = function()
       tex.pri
nt("\string\\numexpr 17\string\\relax")
     end
}
\tt
\directlua{token.set_lua("test", 999)}
\meaning\test\par % expandable luacall 999
\edef\x{\test}\meaning\x\par % macro:->\numexpr 17\relax
\the\test % 17
\directlua{token.set_lua("test", 999, "protected")}
\meaning\test\par % luacall 999
\edef\x{\test}\meaning\x\par % macro:->\test
\the\test % ! You can't use `luacall 999' after \the.
\bye
you can do
\directlua{
    function TestCmd()
      tex.print("\string\\numexpr 17\string\\relax")
    end
}
\protected\def\test{\directlua{TestCmd()}}
or, more efficient:
\directlua{
    function TestCmd()
      tex.print("17")
    end
}
\protected\def\test{\numexpr\directlua{TestCmd()}\relax}
Thanks, this is indeed the workaround that I currently use. However,
the downside is that this has to tokenize the contents of \directlua
every time (and is therefore susceptible to surrounding \catcode
shenanigans) and it expands in at minimum two steps, whereas a luacall
always expands in a single step. But I guess that's what I will have to
live with.

Cheers, Henri
...
Hans
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                                           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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