ORM: add entry_point property to Node and Group

[sphuber]

Fixes #4939

This property will return the entry point of a Node or Group instance
if one is associated with the class, otherwise None is returned.

[chrisjsewell]

Ughh, I'm trying to remove Node attributes, not add them 😅
Why not a classproperty?

[sphuber]

Ughh, I'm trying to remove Node attributes, not add them

#4939 (comment)

I am only conforming to popular demand

Why not a classproperty?

Might as well yeah

[sphuber]

@chrisjsewell @mbercx are we still adding this? Perhaps also in a subnamespace under base? Or are we closing the feature request?

[mbercx]

I think it makes sense to add it under the base name space? Still seems like a useful property to have easy access to.

[sphuber]

I think it makes sense to add it under the base name space? Still seems like a useful property to have easy access to.

One problem with this approach. The NodeBase class returned by Node.base is a property and not an classproperty. This means you could only do Node().base.entry_point and Node.base.entry_point won't be possible. Maybe it is best to keep it top-level then.

[mbercx]

Hmm, yeah, Node().base.entry_point ain't pretty. I think it's a sufficient reason to keep it top level, what do you think @chrisjsewell?

[mbercx]

LGTM 🚀