Should a PortnameSpace be automatically not required if all of its ports are not required either

[espenfl]

If one defines spec.input('somename.someothername', required=False) in a WorkChain and one do not supply that input, it throws and error that it is required. Replacing it to spec.input('somename_someothername', required=False) fixes the problem. Is there a reason for not supporting dots in the name? If so, I guess we should throw another error (if that is possible).

[sphuber]

The dots are supported, it is just working slightly differently than you anticipated. The dot is interpreted as a namespace separator, so the line spec.input('somename.someothername', required=False) will be interpreted as "create a namespace somename and within it, create an input port someothername that is not required". However since the default of ports is for them to be required, and so that includes port namespaces, the namespace somename is required. You can see this when looking at the generated ports by calling print(WorkChain.spec().inputs) which should return something like:

"somename": {
        "_attrs": {
            "default": [], 
            "dynamic": false, 
            "help": null, 
            "required": "True", 
            "valid_type": "None"
        }, 
        "someothername": {
            "name": "someothername", 
            "non_db": "False", 
            "required": "False"
        }
    },
}

If you would have passed the inputs {'somename': {'someothername': input}} it should have worked. If you have ideas how to improve the error message or the documentation, let me know

[espenfl]

Great. This is in fact a useful functionality and what I was originally expected from a dot (except I missed the detail about the namespace requirement). Just ejecting an error message that says that the user need to define namespace if using such syntax would help a lot I think. It has been a while, but I seem to remember that no error or warning was ejected. Do you think that would be possible? Not sure where to put it, otherwise I am happy to submit a PR.

[sphuber]

I think it is very useful to be able to implicitly create namespaces through the use of dots, instead of being forced to create them explicitly. However, it then becomes difficult to warn the user, that any keywords that are passed, such as required will only apply to the leaf port. We could think if we want these keywords to be applied on the intermediate namespaces as well, but it is not trivial to define when this should be done. For example, if the namespace already exist, should it override settings? Or only when it newly creates it. Either way, I think you will always end up with something that is not a 100% intuitive and will always just need to be documented. Perhaps that is also the best solution here

[espenfl]

Agreed. In fact, the only problem with this is the required=False. It should be possible for the user not to supply the variable, regardless of the namespace being there or not (we are creating it dynamically by definition). Would this behavior be possible to fix? E.g. when a namespace is not there, do not raise an error? I think this would be the cleanest. Then we document the dot feature.

[sphuber]

The problem is that currently the namespace itself also has a required attribute. It can for example be the case that a namespace contains multiple ports, some of which are required and some that aren't. Should the requiredness of the namespace be only dependent on the ports it contains? i.e. if it only contains ports that are not required then itself is not required either and as soon it contains one port that is required, then the namespace itself is also required. However, in this scenario, the required attribute on the namespace has no meaning, since it is completely defined by its child ports.
Maybe we should simply get rid of the required attribute for PortNamespaces

[espenfl]

I support this view, that we just inherit. The namespace is probably useless without ports and should also follow their property. If just one port is required, we demand that the namespace is as well.