[Octave-bug-tracker] [bug #55810] sizeof() returns 0 for classdef objects

[Andrew Janke]

URL:
  <https://savannah.gnu.org/bugs/?55810>

                 Summary: sizeof() returns 0 for classdef objects
                 Project: GNU Octave
            Submitted by: apjanke
            Submitted on: Sat 02 Mar 2019 01:27:48 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.4.1
        Operating System: Mac OS

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Details:

It looks like the default implementation of sizeof() returns 0 for
user-defined classdef objects. (I think this also causes the Bytes for
classdef objects in the `whos` output to be displayed as 0.)

IMHO, it would make more sense for the default implementation of sizeof() to 
do a `builtin('struct', x)` on user-defined objects and return that. That
would give you a decent approximation of the Octave-managed raw data being
used by those objects.

To reproduce:

Define MyDumbClass.m:


classdef MyDumbClass

  properties
    data
  endproperties

  methods
    function this = MyDumbClass (data)
      this.data = data;
    endfunction
  endmethods

endclassdef


Create one and check its size:


>> x = MyDumbClass(zeros(1000, 1000))
x =
<object MyDumbClass>

>> sizeof(x)
ans = 0
>> sizeof(x.data)
ans =  8000000


I think that sizeof(x) should be returning 8000000 instead of 0.





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