From dbdd041a6bcdeea639aeb756e051d8f95caccf11 Mon Sep 17 00:00:00 2001
From: Joseph Wright <joseph.wright@morningstar2.co.uk>
Date: Tue, 8 Mar 2022 19:03:59 +0000
Subject: [PATCH] Add interface for overridden instance keys

---
 required/latex-lab/latex-lab-prototype.dtx | 24 ++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/required/latex-lab/latex-lab-prototype.dtx b/required/latex-lab/latex-lab-prototype.dtx
index b957ff5b8..ee971bab0 100644
--- a/required/latex-lab/latex-lab-prototype.dtx
+++ b/required/latex-lab/latex-lab-prototype.dtx
@@ -270,15 +270,19 @@
 % calls instances directly, and this command should be used internally
 % in document-level mark-up.
 %
-% \begin{function}{\prototype_use_instance:nn}
+% \begin{function}{\prototype_use_instance:nn, \prototype_use_instance:nnn}
 %   \begin{syntax}
 %     \cs{prototype_use_instance:nn}
 %     ~~\Arg{object type} \Arg{instance} \meta{arguments}
+%     \cs{prototype_use_instance:nn}n
+%     ~~\Arg{object type} \Arg{instance} \Arg{overrides} \meta{arguments}
 %   \end{syntax}
 %   Uses an \meta{instance} of the \meta{object type}, which will require
 %   \meta{arguments} as determined by the number specified for the
 %   \meta{object type}. The \meta{instance} must have been declared
-%   before it can be used, otherwise an error is raised.
+%   before it can be used, otherwise an error is raised. The \texttt{nnn}
+%   version allows for local overrides of the instance settings using the
+%   additional keyval argument.
 % \end{function}
 %
 % \begin{function}{\prototype_use_template:nnnn}
@@ -460,14 +464,29 @@
 % \end{macro}
 %
 % \begin{macro}{\prototype_use_instance:nn}
+% \begin{macro}{\prototype_use_instance:nnn}
 %   Recover the values and insert the code.
 %    \begin{macrocode}
 \cs_new_protected:Npn \prototype_use_instance:nn #1#2
+  { \prototype_use_instance:nnn {#1} {#2} { } }
+\cs_new_protected:Npn \prototype_use_instance:nnn #1#2#3
   {
     \tl_if_exist:cTF { l_@@_instance_ #1 _ #2 _template_tl }
       {
         \tl_set_eq:Nc \l_@@_assignments_tl
           { l_@@_instance_ #1 _ #2 _pars_tl }
+        \tl_if_blank:nF {#3}
+          {
+            \tl_set:Nx \l_@@_tmp_tl
+              {
+                prototype / #1 /
+                \tl_use:c { l_@@_instance_ #1 _ #2 _template_tl }
+              }
+            \exp_args:NNV \keys_precompile:Nnn
+              \l_@@_tmp_tl \l_@@_tmp_tl {#3}
+            \tl_put_right:NV \l_@@_assignments_tl
+              \l_@@_tmp_tl
+          }
         \use:c
           {
             @@_template_ #1 _
@@ -479,6 +498,7 @@
   }
 %    \end{macrocode}
 % \end{macro}
+% \end{macro}
 %
 % \subsection{Messages}
 %