We need a way to add attributes to vertex::group

[clemens-tolboom]

While trying to fix #36 it seems we need something like a cluster class for graphviz to add local attributes for the cluster like

• title
• defaults for the contained elements like node, edge and graph

We do have a group concept for vertices but their group needs attributes. We can call this a subgraph but that would mean the users of Graph must create these.

A group is just tagging vertice with a belongs to relation.

Kan we call this class Group?

[clue]

I agree that it's very useful to handle groups in an OOP manner 👍 Eventually it should implement the LayoutableInterface, so that each group can be styled independently.

A group is just tagging vertice with a belongs to relation.

Afaict, that's exactly what a subgraph does.

Explicitly creating subgraphs has the benefit of well, being explicit... But then again, we can also provide some convenience SubgraphBuilder class which automatically creates nested subgraphs based on a given separator character?

$builder = new SubgraphBuilder($graph);
$builder->setAutoCreateOnGet(true);
$builder->setNestingSeparator(':');

$subgraph = $builder->getSubgraphNested('this:is:on:level4');

$subgraph->createVertex('a vertex within level4 subgraph');

I'm trying not to clutter this ticket with my SubgraphBuilder idea, but getting back on topic, I think we should stick with the name Subgraph.

[clue]

Ping @clemens-tolboom, what's the status on this ticket?

GraphViz has been split off via #115, while #103 introduced general purpose attributes for all entities.

Afaict this ticket asks for a way to assign attributes to a group of entities at once?

[clue]

Closed via #168, see graphp/graphviz#38 instead.