When to write operations in 'Forward' and when to write in 'Message'?

[ShengzheXu]

Hey guys. Maybe this is a trivial question.. I'm wondering when should I implement my formulations in the 'forward' method and when should I implement them in the 'message' (propagate) method?

For example, some tutorials implement the gcn_norm in the forward method of the GCNconv class, while some other tutorials also implement the gcn_norm in the message method.

Could some one help explain this a bit, like what's the difference of implementation at the two places. Appreciate for any advice.

[rusty1s]

There doesn't exist a rule of thumb for this and its mostly user-preference. In general, it is preferred to compute all edge-level representations directly inside message since you do not need to take care of gathering features, etc. However, I agree that we are breaking with this pattern by ourselves as well, e.g., in gcn_norm :)

[ShengzheXu]

Thanks Matthias!