Relegate the on-close for emergencies

inst/private/python_ipc_popen2.m

@@ -1,5 +1,6 @@
 %% Copyright (C) 2014-2019, 2022 Colin B. Macdonald
 %% Copyright (C) 2018, 2020 Mike Miller
+%% Copyright (C) 2022 Alex Vong
 %%
 %% This file is part of OctSymPy.
 %%
@@ -34,7 +35,7 @@
 
 function [A, info] = python_ipc_popen2(what, cmd, varargin)
 
-  persistent cleanup fin fout pid
+  persistent emergency_cleanup fin fout pid
 
   py_startup_timeout = 30;  % seconds
 
@@ -43,11 +44,29 @@
   info = [];
 
   if (strcmp(what, 'reset'))
-    cleanup = [];  % triggers a call to reset function
+    if (~ isempty (pid))
+      if (verbose)
+        disp ('Closing the Python communications link.')
+      end
+    end
+    A = true;
+    if (~ isempty (fin))
+      % produces a single newline char: not sure why
+      t = fclose (fin);
+      fin = [];
+      waitpid (pid);
+      pid = [];
+      A = A && (t == 0);
+    end
+    if (~ isempty (fout))
+      t = fclose (fout);
+      fout = [];
+      A = A && (t == 0);
+    end
+    emergency_cleanup = [];  % note: triggers emergency file-close
     fin = [];
     fout = [];
     pid = [];
-    A = true;
     return
   end
 
@@ -74,9 +93,13 @@
       error('popen2() failed');
     end
 
-    % this will be called when we `clear cleanup`: avoids dangling file handles
-    cleanup = onCleanup (@() python_ipc_popen2_reset (fin, fout, pid));
-
+    then = @(f, g) g (f ());
+    % will be called when we `clear functions`: avoids dangling file handles
+    emergency_cleanup = onCleanup (@() ...
+                          then (@(varagin) ...
+                                 [is_valid_file_id(fin) && fclose(fin), ...
+                                  is_valid_file_id(fout) && fclose(fout)], ...
+                                @(varargin) ~isempty(pid) && waitpid(pid)));
     headers = python_header();
     fputs (fin, headers);
     fprintf (fin, '\n\n');