[Dev-luatex] [PATCH] Allow literal # in argument text by escaping

[Hans Hagen]

On 5/27/2019 5:52 PM, Marcel Fabian Krüger wrote:

> Anyway I do not understand what you say with your last statement. How would
> they help solving the original problem of `#` delimiters? As far as I
> can tell they are rewritten into "normal" positional arguments, so I do
> not see how they could help.
It's indeed unrelated so of no help and anyway something context 
specific that is nto used that often (performance wise, it started out 
as an experiment as usual). Anyhow, your patch deals with a very 
specific case and because normally the way to deal with this is via 
catcode settings it is not something that will end up in the engine. It 
deals with a # as delimiter but if these occur in a document then other 
cases of # will still be an issue. Making this one exception / catch is 
not that consistent. One way out is to not bark on # (which are special) 
but on the other hand this is a tex property that has been dealt with 
for ages in macro packages and patching the engine for that is no option 
(once we start along that route we end up with lots of curious patches 
for rare cases which is not what we have in mind).

fwiw: I have considered extending the macro handler, e.g. with more than 
9 arguments which is not that hard but it makes not much sense. Macro 
packages have to deal with other engines too.

note: As one of the complaints about luatex is that we kept adding stuff 
which is then voiced as equivalent for it being not stable which in turn 
becomes kind of boring / annoying to endure, at some point one has to 
decide to freeze functionality. So don't expect much additions. I'm 
considering a few low level optimizations and non intrusive thingies as 
side effect of some experiments but that will be a once-in-a-while 
adventure in sync with version bumps in the first digit (like 1.20, 1.30 
  and so).

Hans

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