Dear all, when a graph is immutable, there are meaningless error messages that make it hard for the user to guess what is going on (see below).
When I create graphs like this, I know perfectly well what is going on. However, when this is done in a cached method, it is hard for the user to figure out the problem, isn't it? I'm currently working on #28828 <https://trac.sagemath.org/ticket/28828> and returning an immutable graph seems to leave the user clueless about why the code breaks. Of course one could just cache a private method and return a copy or manually cache it, but that seems to be against the point of @cached_method. Any suggestion for a good fix? Am I missing something? Thanks, Jonathan sage: G = Graph(immutable=True) sage: G.add_edge([0,1]) --------------------------------------------------------------------------- NotImplementedError Traceback (most recent call last) <ipython-input-20-2543f955ba93> in <module>() ----> 1 G.add_edge([Integer(0),Integer(1)]) /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/generic_graph.py in add_edge(self, u, v, label) 10816 pass 10817 > 10818 self._backend.add_edge(u, v, label, self._directed) 10819 10820 def add_edges(self, edges, loops=True): /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/base/graph_backends.pyx in sage.graphs.base.graph_backends. GenericGraphBackend.add_edge (build/cythonized/sage/graphs/base/ graph_backends.c:1694)() 100 NotImplementedError 101 """ --> 102 raise NotImplementedError() 103 104 def add_edges(self, edges, directed): NotImplementedError: sage: G = DiGraph([[0,1]], immutable=True) sage: G.reverse_edges(G.edges()) --------------------------------------------------------------------------- NotImplementedError Traceback (most recent call last) <ipython-input-22-b7007f357194> in <module>() ----> 1 G.reverse_edges(G.edges()) /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/digraph.py in reverse_edges(self, edges, inplace, multiedges) 2074 tempG = self if inplace else copy(self) 2075 for e in edges: -> 2076 tempG.reverse_edge(e,inplace=True,multiedges=multiedges) 2077 if not inplace: 2078 return tempG /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/digraph.py in reverse_edge(self, u, v, label, inplace, multiedges) 1968 "multiedges is True or False.") 1969 else: -> 1970 tempG.delete_edge(u, v, label) 1971 tempG.add_edge(v, u, label) 1972 /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/generic_graph.py in delete_edge(self, u, v, label) 11130 u, v = u 11131 label = None > 11132 self._backend.del_edge(u, v, label, self._directed) 11133 11134 def delete_edges(self, edges): /home/jonathan/Applications/sage/local/lib/python3.7/site-packages/sage/ graphs/base/graph_backends.pyx in sage.graphs.base.graph_backends. GenericGraphBackend.del_edge (build/cythonized/sage/graphs/base/ graph_backends.c:2273)() 248 NotImplementedError 249 """ --> 250 raise NotImplementedError() 251 252 def del_vertex(self, v): NotImplementedError: -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/34c6ccdf-1ca6-4831-a986-2446b3b705f9%40googlegroups.com.
