Remove BlockBase.parent and BlockBase.next properties

[adroitwhiz]

Currently, the BlockBase class has the properties parent and next, which appears to be the IDs of its parent block and the next block in the stack respectively.

They don't appear to be used anywhere in the export code, and could make it much harder to manipulate the block tree.

It looks like they're modeled after the SB3 JSON structure, but given that sb-edit's API has already deviated from SB3, it's unnecessary to have them. Can/should these properties be removed?

[adroitwhiz]

/cc @PullJosh for your thoughts on this.

Also @towerofnix, parent and next are never accessed from BlockBase in the toSb3 code, right? I did a quick search through and didn't find any usage of them (it looks like the parent and next properties on the serialized blocks are calculated in other ways, which is good), but I may be missing something.

[PullJosh]

Removing both makes sense. 👍

[towerofnix]

@adroitwhiz Yep! It's safe to remove parent and next. I was slightly concerned about "next" but that block link is calculated by serializeBlockStack without reference to that property.

[towerofnix]

@adroitwhiz Do you think it still makes sense to remove these relational properties? It's worth noting that it will have an influence on how "mutation" functions are written (for lack of a proper term, currently) — any function which performs static analysis and replaces input blocks with an equivalent but different set.

(We don't have any of those yet, and maybe we won't include any as built-in behavior, but sb-edit is ostensibly about manipulating projects including blocks, so it's worth considering for the sake of library-consuming code too. By removing parent and next, we would rule out certain code patterns for any modular "mutations". That could be a good thing! But I'm not sure.)

[adroitwhiz]

I think removing these would actually make it much easier to manipulate block stacks. It might even open up the possibility of placing the same block object in multiple stacks at once, which you can't do right now.

[towerofnix]

Sure thing! I think the styles it rules out forces you into much cleaner ones as a consequence, which is a win in my books 📦