use plain inheritance instead of class variables

[danieleades]

trafficstars

use plain inheritance instead of class variables for Graph factory methods.

from discussion in #4014 it seems these factory methods were implemented as class methods for performance reasons, that no longer hold.

Using plain methods and inheritance instead of patching class methods is far less 'magic', and therefore easier to reason about. It uses plain old python inheritance instead.

there's another benefit too- if this library starts using type annotations, then an IDE or linter will ensure that consumers correctly subclass these factory methods, including enforcing return types that implement the Mapping protocol ("dict-like"). The use of class methods in the previous implementation confounds this static analysis

eg.

from collections.abc import Mapping

...

    def node_dict_factory(self) -> Mapping[X, Y]:
        """Factory function to be used to create the dict containing node attributes, keyed by node id."""
        return {}

where X is the node id type, and Y is the node attribute type

[danieleades]

FYI @NeilGirdhar

[NeilGirdhar]

I love this and hope the networkx team will as well.

enforcing return types that subclass dict

FYI I think this (and the various comments in the code) should say Mapping instead of dict. The phrase "dict-like object" should probably be "mapping" or collections.abc.Mapping.

[danieleades]

FYI I think this (and the various comments in the code) should say Mapping instead of dict. The phrase "dict-like object" should probably be "mapping" or collections.abc.Mapping.

Yeah I imagine that's probably the case

Edit: updated summary

[danieleades]

@MridulS this has been open for coming up on on 7 months now. How can I progress this?

@jarrodmillman, @dschult ?

[danieleades]

@MridulS this has been open for coming up on on 7 months now. How can I progress this?

@jarrodmillman, @dschult ?

ping maintainers?

[danieleades]

ping @rossbar