Introduce KnobT, fix signature for nuke.zoom and nuke.filename, use N…

[herronelou]

Introduce KnobT, fix signature for nuke.zoom and nuke.filename, use NodeT instead of Node most places.

[chadrik]

Hi, thanks for the contribution.

There's no need to replace everything with NodeT and KnobT. TypeVars are only required when you want to create a relationship between two or more type annotations. There are some good examples here: https://filipgeppert.com/mypy-advanced-examples.html

NodeT is used for one specific case:

class NodeConstructor(Generic[NodeT]):
    @classmethod
    def __init__(self, *args, **kwargs) -> None: ...
    def __call__(self, *args, **kwargs) -> NodeT: ...
    def __hash__(self) -> Any: ...

class Nodes:
    @classmethod
    def __init__(self, *args, **kwargs) -> None: ...
    def __hash__(self) -> Any: ...
    def __getattr__(self, item) -> NodeConstructor[Node]: ...

    Group : NodeConstructor[Group]
    BackdropNode : NodeConstructor[BackdropNode]
    Gizmo : NodeConstructor[Gizmo]
    Viewer : NodeConstructor[Viewer]

nodes: Nodes

This ensures that a type analyzer knows that nodes.Group.__call__() (i.e. nodes.Group()) returns an instance of Group, and nodes.BackdropNode() returns a BackdropNode, etc.

Can you remove the KnobT and NodeT changes, please, unless there is a relationship that requires a TypeVar? Then I'll review the remaining parts.