Refuse to alter read-only elements at runtime

[mudpy.git] / mudpy / misc.py

diff --git a/mudpy/misc.py b/mudpy/misc.py
index af5427a..157096c 100644 (file)
--- a/mudpy/misc.py
+++ b/mudpy/misc.py
@@ -154,6 +154,12 @@ class Element:
 
     def set(self, facet, value):
         """Set values."""
+        if not self.origin.is_writeable() and not self.universe.loading:
+            # break if there is an attempt to update an element from a
+            # read-only file, unless the universe is in the midst of loading
+            # updated data from files
+            raise PermissionError("Altering elements in read-only files is "
+                                  "disallowed")
         if facet in ["loglevel"]:
             value = int(value)
         if not self.has_facet(facet) or not self.get(facet) == value:
@@ -347,6 +353,7 @@ class Universe:
         self.contents = {}
         self.default_origins = {}
         self.directions = set()
+        self.loading = False
         self.loglines = []
         self.private_files = []
         self.reload_flag = False
@@ -375,6 +382,9 @@ class Universe:
     def load(self):
         """Load universe data from persistent storage."""
 
+        # while loading, it's safe to update elements from read-only files
+        self.loading = True
+
         # it's possible for this to enter before logging configuration is read
         pending_loglines = []
 
@@ -425,6 +435,10 @@ class Universe:
         for element in self.contents.values():
             element.update_location()
             element.clean_contents()
+
+        # done loading, so disallow updating elements from read-only files
+        self.loading = False
+
         return pending_loglines
 
     def new(self):