Validate the . dot notation in Kedro pipeline

[noklam]

Description

kedro-org/kedro-viz#1522

User are confused with disconnected graph in kedro-viz
https://docs.kedro.org/en/stable/tutorial/add_another_pipeline.html

Context

Internally . is reserved for namespace, but Kedro Framework never block this/validate this eagerly. So user can create something that looks like a namespace pipeline but isn't.

User should use the namespace argument instead of using inputs=namespace.my_input.

kedro/kedro/pipeline/modular_pipeline.py

Lines 225 to 226 in 3d41425

	def _prefix_dataset(name: str) -> str:
	return f"{namespace}.{name}"

Internally, dot is used for namespace. Noted that even Node have _namespace attribute but it is actually more about which pipeline it is belong to. It's ambiguous what's the namespace of a node because the input and output can come from different namespace.

Possible Implementation

Validate this behavior and block it. We probably cannot validate the node because it is a valid internal representation. We can however validate the argument in node constructor if it is desired.

Possible Alternatives

Validate this behavior and raise warning.

[datajoely]

There is a wider point about how we internally store namespaces in the catalog with __ and it's weird!

[MehdiNV]

Leaving notes for the future:

Some validation is completed, but like Nok notes above, may not be usable as we prefix. Regardless, may be of interest in the future - check the highlighted parts below for how Kedro already attempts some validation:

[astrojuanlu]

For now, let's add a WARNING to the logs when the user uses a . in an input or output specifier.