configs/manager.py: Add method "read_userconfig()"

This "read_userconfig()" method is specifically used to load the user
configuration file, and record the absolute path of the configuration
file, which allows the use of relative path to specify the input files
(e.g., galactic/synchrotron/template) for simulation within the
configurations.

1 files changed, 35 insertions, 3 deletions

diff --git a/fg21sim/configs/manager.py b/fg21sim/configs/manager.py
index 662c93d..caf0bc4 100644
--- a/fg21sim/configs/manager.py
+++ b/fg21sim/configs/manager.py
@@ -51,16 +51,48 @@ class ConfigManager:
 
         Parameters
         ----------
-        config : str, list of str
+        config : str, list[str]
             Input config to be validated and merged.
             This parameter can be the filename of the config file, or a list
             contains the lines of the configs.
         """
-        newconfig = ConfigObj(config, interpolation=False,
-                              configspec=self._configspec)
+        try:
+            newconfig = ConfigObj(config, interpolation=False,
+                                  configspec=self._configspec)
+        except ConfigObjError as e:
+            raise ConfigError(e)
         newconfig = self._validate(newconfig)
         self._config.merge(newconfig)
 
+    def read_userconfig(self, userconfig):
+        """Read user configuration file, validate, and merge into the
+        default configurations.
+
+        Parameters
+        ----------
+        userconfig : filename
+            Filename/path to the user configuration file.
+
+        NOTE
+        ----
+        The user configuration file can be loaded *only once*,
+        or *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 hasattr(self, "userconfig"):
+            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)
+        #
+        self.read_config(config)
+        self.userconfig = os.path.abspath(userconfig)
+
     def _validate(self, config):
         """Validate the config against the specification using a default
         validator.  The validated config values are returned if success,