595 Allow using empty indices for datastub

[ehennestad]

Fix #595

Motivation

Fix issue.

How to test the behavior?

See issue #595

Checklist

• Have you ensured the PR description clearly describes the problem and solutions?
• Have you checked to ensure that there aren't other open or previously closed Pull Requests for the same change?
• If this PR fixes an issue, is the first line of the PR description fix #XX where XX is the issue number?

[ehennestad]

@lawrence-mbf I would value your input here.

The proposed fix works in the specific situation, but if you have ideas on how to improve this, or if there are things I have overlooked please let me know.

[codecov]

Codecov Report

Attention: Patch coverage is 15.38462% with 11 lines in your changes missing coverage. Please review.

Project coverage is 90.42%. Comparing base (bc4b87d) to head (1b4dbfb).

Files with missing lines	Patch %	Lines
+types/+untyped/@DataStub/load_mat_style.m	15.38%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #605      +/-   ##
==========================================
- Coverage   90.63%   90.42%   -0.22%     
==========================================
  Files         106      106              
  Lines        4686     4698      +12     
==========================================
+ Hits         4247     4248       +1     
- Misses        439      450      +11     

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[lawrence-mbf]

@ehennestad Does this work with HDF5 reference types? Very clever, I did not know left-hand side colon assignment preserved types.

[lawrence-mbf]

This conditional adds support for this syntax:

ds = types.untyped.DataStub(...);
emptytype = ds([]);

and

emptytype = ds('');

But not

emptytype = ds();

Is that the intention here?

[ehennestad]

Yeah this should be updated.
emptytype = ds([]); should be supported, but neither emptytype = ds(''); or emptytype = ds(); should be

[ehennestad]

Based on MATLAB's builtin behavior, it should perhaps be kept the way it is:

>> s = struct('a', num2cell(1:10))

s = 

  1×10 struct array with fields:

    a

>> s([])

ans = 

  0×0 empty struct array with fields:

    a

>> s('')

ans = 

  0×0 empty struct array with fields:

    a

>> s()

ans = 

  1×10 struct array with fields:

    a