it needs a bit of thinking
(even bidi) ... it compares to global and
local bodyfonts
what if a page break occurs in the middle of japanese local text
while
the global script is chinese
I can understand your concerns.
Another way is to add additional commands which let you set the script
for all environments (body text + footnotes).
1. Add "global" to the attribute definition (or add another keyword
which doesn’t add the reset to the local token list but using "global"
should be enough).
%%%%%% attr-ini.mkiv
\def\attr_basics_define_indeed#1[#2][#3]%
{\ifcsname\??attributecount#2\endcsname\else
\scratchcounter\clf_defineattribute{#2}{#1}\relax
%\writestatus\m!system{defining #1 attribute #2 with number
\number\scratchcounter}%
\expandafter\attributedef\csname\??attributecount#2\endcsname\scratchcounter
\expandafter\newconstant \csname\??attributeid#2\endcsname
\csname\??attributeid#2\endcsname\scratchcounter
% some attributes are always global
\doifelseinset\s!global{#3}%
{\etoksapp\t_attr_list_global{\csname\??attributecount#2\endcsname\attributeunsetvalue}}%
- {\etoksapp\t_attr_list_local
{\csname\??attributecount#2\endcsname\attributeunsetvalue}}%
+ {\doifnotinset\s!none{#3}
+ {\etoksapp\t_attr_list_local
{\csname\??attributecount#2\endcsname\attributeunsetvalue}}}%
\doifinset\s!nomath{#3}%
{\etoksapp\t_attr_list_nomath{\csname\??attributecount#2\endcsname\attributeunsetvalue}}%
% here public means 'visible' so it's not to be confused with
'public' at the lua end
\doifinset\s!public{#3}%
{\expandafter\let\csname#2\s!attribute\expandafter\endcsname\csname\??attributeid#2\endcsname}%
\fi}
%%%%%%
2. Create a flag which can be used to prevent the reset of the
attributes when you use the global-commands. The old \setscript command
will be a synonym for the local settings while you can use the global
command when the document contains only one language.