filename supplied in __init__ will be read last, so it has highest priority

userconfig/cfgfile.py

@@ -12,8 +12,6 @@ class Conf(object):
         if debug:
             self.set_debug(debug)
         filenames = []
-        if filename:
-            filenames.append(filename)
         if not force_filename:
             # default config files are $HOME/etc/userconfig2.conf and
             # {sys.prefix}/etc/userconfig2.conf
@@ -21,6 +19,9 @@ class Conf(object):
                 filenames.append(f'{os.environ.get("HOME")}/etc/userconfig2.conf')
             if os.path.isfile(f'{sys.prefix}/etc/userconfig2.conf'):
                 filenames.append(f'{sys.prefix}/etc/userconfig2.conf')
+        # supplied filename will be read last, has highest priority
+        if filename:
+            filenames.append(filename)
         ret = self.set_filenames(filenames)
         if not ret:
             raise ValueError(f'Cannot open either configuration file: {",".join(filenames)}')