Streamlining axis size

[Tomaz-Vieira]

This PR tries to streamline axis sizes, so that there are fewer special cases and so that it is easier to verify their correctness:

• All axes sizes are FixedSize | ParameterizedSize | SizeReference;
  • No more ints or strs or None or whatver;
• Checking that the axes sizes are good is done in one go, after resolving all references;
• Unit is only specified in the non-reference sizes, so they can't conflict with the referent;
• Channel names are streamlined; either give all names or a reference and prefix/suffix;
• Reference-to-reference-to-reference... is supported;
• There is reference-loop detection;
• Less code;

TODO:

• Check that channel axes don't reference non-channel axes
• Special-case for batch axes? Does it come into play when looking at the test tensors?
• Probably move TensorDataDescr into ChannelAxis

[FynnBe]

Special-case for batch axes? Does it come into play when looking at the test tensors?

For simplicity and consistency we (should) expect the test tensors to have singleton batch axes if their description is it. In other words, the test tensor should match the description exactly

Probably move TensorDataDescr into ChannelAxis

I don't think so. I wanted that initially, but then I realized that tensors may not have an explicit (singleton) channel axis. And we'd still need the data description

[FynnBe]

moving the unit into the size means we break compatibility with https://ngff.openmicroscopy.org/latest/#axes-md
I think we should try to stay directly compatible.

[FynnBe]

this is also mixing the pixel size with the unit.
the unit should go with the scale. together they describe the distance of two pixels/frames.
The size is intended to describe the number of pixels/frames, i.e. the tensor shape

[FynnBe]

why change the field name to batch_size?

[FynnBe]

ah.. found the size property..
how about we just use ParameterizedSize(min=1, step=1) as a default value and leave the field as size?

[Tomaz-Vieira]

how about we just use ParameterizedSize(min=1, step=1) as a default value and leave the field as size?

But this would type this field as Optional[ParameterizedSize], which would allow it to be something like ParameterizedSize(min=3, step=10), and that seems to go against the original intention of having it be either exactly 1 or any number picked by the runtime

[FynnBe]

Ha, true!
How about

class ParameterizedBatchSize(ParametrerizedSize):
   min: Literal[1]
   step: Literal[1]

and

class BatchAxis....
    size: Union[Literal[1], ParameterizedBatchSize] = ...

?