Yes, I think this issue could be left open, but let's octave maintainers decide.

I also think that a possible solution could be to redefine numel, or simply removing the definition of numel in your class, so that 1 is always returned.

A better long term solution would be to make octave compatible with Matlab in that aspect, by implementing and making use of function numArgumentsFromSubscript. Maybe jwe or another octave developer would like to have a go with it.

Here is the reference for Matlab's numArgumentsFromSubscript

https://www.mathworks.com/help/matlab/ref/numargumentsfromsubscript.html

Ayup, that sure smells similar.

I do not think I am defining an `end` method; I didn't even know that was a thing. But the behavior described there looks awful similar to what I'm experiencing here.

I'll read through that in detail and play around with what they're describing when I get a chance.

Thanks!

Hi folks. In my Tablicious package (https://github.com/apjanke/octave-tablicious) I have defined a `table` class using a classdef (https://github.com/apjanke/octave-tablicious/blob/3b905b4d190d4869bb6cde2baa37b9273a61822b/inst/table.m), and given it subsref and subsasgn methods, plus a lot of other structure-and-size-related overridden methods. For .-indexing with these, the intent is for you to be able to index a variable (aka "column") by name, and either get the entire variable out, or assign a new array to the whole thing.

Reading the variables out works:

>> t = table([11;22;33], {'uno';'dos';'tres'}, 'VariableNames', {'X','S'});
>> t.X
ans =
   11
   22
   33

But attempting to assign to them errors out:

>> t.X = [1;2;3];
error: invalid dot name structure assignment because the structure array is empty.  Specify a subscript on the structure array to resolve.
>> t.foobar = [1;2;3]
error: invalid dot name structure assignment because the structure array is empty.  Specify a subscript on the structure array to resolve.

The error appears to be happening in the Octave interpreter before my subsasgn method ever gets called: If I put a `keyboard` statement as the first line in my table.subsasgn implementation, it never gets hit in this case.

Am I doing something wrong here? Or could this be an issue in the Octave interpreter's handling of subsasgn/subsref on existing objects, maybe in regards to how it interacts with numel or other size-related methods? Maybe it's implicitly calling one of the size-related methods to get some info about the assignment target and not happy with what it's hearing?

I've tried to come up with a minimal reproducible example, but haven't been able to trigger this behavior with a simpler classdef. (See attached shtable.m file.)

Original bug in the Tablicious project: https://github.com/apjanke/octave-tablicious/issues/80