configs/manager.py: Reset before loading user config file again

Originally, the user configuration file is only allowed to load once,
and prevent any future loading of user configuration file.

This change allows load user configuration file again by resetting the
current configurations to defaults before loading.

1 files changed, 10 insertions, 12 deletions

diff --git a/fg21sim/configs/manager.py b/fg21sim/configs/manager.py
index d03479e..ff950bb 100644
--- a/fg21sim/configs/manager.py
+++ b/fg21sim/configs/manager.py
@@ -69,11 +69,11 @@ class ConfigManager:
     userconfig : str
         The filename and path to the user-provided configurations.
         NOTE:
-        - This attribute only presents after loading the user configuration
-          by ``self.read_userconfig()``;
+        - This attribute has valid value only after loading the user
+          configuration by ``self.read_userconfig()``;
         - This attribute is used to determine the absolute path of the
           configs specifying the input templates or data files, therefore
-          allow the use of relative path for those configs.
+          allow the use of relative path for those config options.
     """
     # Path to the user provided configuration file, which indicates user
     # configurations merged if not ``None``.
@@ -126,21 +126,19 @@ class ConfigManager:
 
         NOTE
         ----
-        The user configuration file can be loaded *only once*, i.e.,
-        *only one* user configuration file supported.
-        Since the *path* of the user configuration file is recorded, and
-        thus allow the use of *relative path* of some input files (e.g.,
-        "galactic/synchrotron/template") within the configurations.
+        If a user configuration file is already loaded, then the
+        configurations are *reset* before loading the supplied user
+        configuration file.
         """
-        if self.userconfig is not None:
-            raise ConfigError('User configuration already loaded from "%s"' %
-                              self.userconfig)
-        #
         try:
             config = open(userconfig).read().split("\n")
         except IOError:
             raise ConfigError('Cannot read config from "%s"' % userconfig)
         #
+        if self.userconfig is not None:
+            logger.warning('User configuration already loaded from "%s"' %
+                           self.userconfig)
+            self.reset()
         self.read_config(config)
         self.userconfig = os.path.abspath(userconfig)
         logger.info("Loaded user config: {0}".format(self.userconfig))