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: