align dimension types to offset types

[jshook]

What is the suggestion?
Make dimensions long[] by default.

Presently you get dimensions like this:

int[] dimensions= dataset.getDimensions()
dimensions[0]=1; // select one row slice

And then you might set offsets like this:

long[] offsets = new long[dimensions.length];
offsets[0]=myoffset;

It seems that the magnitude of offsets is bounded by the magnitude of the dimensions, and thus the data types appear misaligned.

Instead, dimensions should be provided as and stored as longs. It should at least be possible to describe and interact with datasets which have such dimensions.

It would align the scalar bounds between possible offsets and possible dimensions and allow users to address larger datasets.

Notes
The HDF5 spec allows the size of these dimension values to be set in the superblock header. The jhdf library already supports reading this, but if someone were to present a dataset which used 64-bit Size of Lengths, there would be an issue even seeing the dimensions.

[jamesmudd]

Sorry for the slow reply. I have thought about this a few times. It did used to be long[] 1fdaa9c I cant remember the exact reasons why it was changed now, but at the time it seemed reasonable. Maybe you can did though the history a little more.

In general I think we probably should have long[] it just allows for wider support, so if you want to attempt this change I would be willing to accept it. I think it might prove a little tricky see comments here #283

Maybe we can add a compatibility method like getDimensionsAsInt to allow a easier migration.