add 'core' prefix to entry points defined by aiida-core

[ltalirz]

In order to be in line with rules for plugins and to avoid polluting the global namespace, the entry points defined by aiida-core should be prefixed by 'core.', e.g. core.structure.

See also discussion here

Planned for v2.0.0

[sphuber]

Just happened to come across this and wanted to mention that core.structure might not be the best example as we might want to move that class to a separate plugin package. core.int, core.float etc. would of course be internal types that would need the prefix

[ltalirz]

@sphuber just checking what's the consensus on that one... do we leave it untouched in 2.0?

[sphuber]

Hmm, forgot about this one. Originally I would have said to coordinate this with the moving out of material science specific plugins to a separate package since that would anyway require entry points to be changed. But maybe we can already preempt this change for the plugins that should stay regardless. I am thinking if we can do this in a backwards-compatible way and deprecate the old entry point names.

We could change the entry point names for internal plugins (Int, Float) etc. to add the core. prefix and add a database migration that updates the node_type from affected nodes, e.g. data.int.Int. would become data.core.init.Int.. This way, after the migration anyone loading a node with data.core.int.Int. would get the correct class back. The only thing that would break in this case (if I am not forgetting anything) is the line

Int = DataFactory('int')

which would have to be changed to

Int = DataFactory('core.int')

However, I think we can deprecate this by having a look up list in the DataFactory that knows about the migrated entry points and in those cases, prints a warning notifying the user of the new entry point name. Then at some point we can remove this and everything should be fine. I think this approach might work and therefore may be interesting to consider adding for v2.0