set_lua freezes control sequences

set_lua freezes control sequences

[Marcel Fabian Krüger]

Hi,

I noticed that recent LuaMetaTeX versions treats control sequences
defined using token.set_lua with `value` or `condition` as frozen and
does not allow redefining them. Given that these are not macros, we also
can't "unfreeze" them using \unletfrozen.

  1. Would it be possible to add a variant of Lua value and condition
  control sequences that are not frozen?

  2. Also is there some way to disable the \frozen restrictions
  altogether? Maybe \suppressfrozenerror?

  3. I also noticed that `token.set_lua` is not affected by control
  sequences being frozen. Therefore it allows redefining frozen
  control sequences which seems inconsistent.

Best regards,
Marcel
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Re: set_lua freezes control sequences

[Hans Hagen]

On 8/25/2020 3:59 PM, Marcel Fabian Krüger wrote:
> Hi,
> 
> I noticed that recent LuaMetaTeX versions treats control sequences
> defined using token.set_lua with `value` or `condition` as frozen and
> does not allow redefining them. Given that these are not macros, we also
> can't "unfreeze" them using \unletfrozen.
> 
>    1. Would it be possible to add a variant of Lua value and condition
>    control sequences that are not frozen?
> 
>    2. Also is there some way to disable the \frozen restrictions
>    altogether? Maybe \suppressfrozenerror?
> 
>    3. I also noticed that `token.set_lua` is not affected by control
>    sequences being frozen. Therefore it allows redefining frozen
>    control sequences which seems inconsistent.
It's all on purpose. Btw, these mechanisms are very experimental (and 
undocumented and might to evolve).

Hans

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Re: set_lua freezes control sequences

[Marcel Fabian Krüger]

On Tue, Aug 25, 2020 at 04:48:27PM +0200, Hans Hagen wrote:
> > I noticed that recent LuaMetaTeX versions treats control sequences
> > defined using token.set_lua with `value` or `condition` as frozen and
> > does not allow redefining them. Given that these are not macros, we also
> > can't "unfreeze" them using \unletfrozen.
> > 
> >   1. Would it be possible to add a variant of Lua value and condition
> >   control sequences that are not frozen?
> > 
> >   2. Also is there some way to disable the \frozen restrictions
> >   altogether? Maybe \suppressfrozenerror?
> > 
> >   3. I also noticed that `token.set_lua` is not affected by control
> >   sequences being frozen. Therefore it allows redefining frozen
> >   control sequences which seems inconsistent.
> It's all on purpose. Btw, these mechanisms are very experimental (and 
> undocumented and might to evolve).

I know, but they are fun to play with. Especially the `value`
kind was one of the most important things I always missed in LuaTeX.

Marcel
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