[NTG-context] protected macro vs protected luacall

[Henri Menke]

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


Cheers, Henri

> 
> Hans
> 
> 
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>                                            Hans Hagen | PRAGMA ADE
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