Should we treat the dictionary of nodes in graph as a defaultdict instead of a normal dict?

[DanielPerezJensen]

Currently when we retrieve a node from the beliefs (graph) that doesn't yet exist we either get None or a node (from self.beliefs.get_node(coords)). But wouldn't it make more sense to simply treat the dictionary of nodes as a default dictionary, with a default value of an empty Node object? Like so:

from collections import defaultdict

self.nodes = defaultdict(Node)

Then now if we access the self.nodes dictionary for a key that does not yet exist it generates an empty node object and returns that instead of None or yielding an error.

[dorian4840]

We could do that but, a) an empty node isn't connected to its neighbours and navigation makes use of what the neighbours of a node are. And b) most of the time when a node isn't found that means that there is something wrong in the code (at least in the graph.py), in this case a KeyError is more useful than the program creating it's own node.

What I could do is improve beliefs.get_node(coords), so that when a node isn't found it does return a new node (which (if possible) will be connected to its neighbours). This way you get the same result but we hold a bit more control.