bugGNU Octave - Bugs: bug #55983, 'x(ix) = []' deletion syntax does...

 
 

bug #55983: 'x(ix) = []' deletion syntax does not work for objects

Submitter:  Andrew Janke <apjanke>
Submitted:  Fri 22 Mar 2019 11:38:37 PM UTC
 
Category:  Interpreter Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * 5.1.0 Operating System:  * Any
Fixed Release:  None Planned Release:  None
* Mandatory Fields

Add a New Comment (Rich Markup)
   

Comment Type & Canned Response:
       

 

Sun 24 Mar 2019 03:51:53 PM UTC, comment #4: 

> MyDumbClass has no subsasgn: isn't that involved in making this work?


It shouldn't be. There should be a default implementation that works like it does for structs. Overriding subsasgn and related methods should only be necessary if you have a custom internal array representation, for example, if you're writing a planar-organized object.

Andrew Janke <apjanke>
Sun 24 Mar 2019 03:14:15 PM UTC, comment #3: 

MyDumbClass has no subsasgn: isn't that involved in making this work?  I definitely had to implement this operation myself in `@sym`.

Colin Macdonald <cbm>
Sat 23 Mar 2019 04:25:26 AM UTC, comment #2: 

> 2. How do you know its not a problem with your `packajoozle` class?


The PkgVer class is very simple. But, valid question.

Here's a simpler reproduction case. I have a MyDumbClass.m, the entirety of which is this:

classdef MyDumbClass

  properties
    x = 42;
  endproperties

endclassdef

Same behavior:

>> x = MyDumbClass
x =
<object MyDumbClass>

>> xx = x;
>> xx(2) = x;
>> xx(3) = x;
>> xx(2) = []
error: cannot convert `null_matrix' into `object'
>>

Andrew Janke <apjanke>
Sat 23 Mar 2019 12:38:59 AM UTC, comment #1: 

Interestingly, this does work with Symbolic using old style @class:

>> syms x
>> A = [x 2*x 3*x]
A = (sym) [x  2⋅x  3⋅x]  (1×3 matrix)
>> A(2) = []
A = (sym) [x  3⋅x]  (1×2 matrix)

1.  I don't remember this regressing when we tried to port Symbolic to classdef (https://github.com/cbm755/octsympy/pull/590)

2.  How do you know its not a problem with your `packajoozle` class?

3.  IIRC, there were some subtle differences between Octave and Matlab: how to make this work might've been one of them...

Colin Macdonald <cbm>
Fri 22 Mar 2019 11:38:37 PM UTC, original submission:  

The special 'x(ix) = []' syntax is supposed to remove identified elements from the array x, regardless of x's type. That is, [] may be a double, but it doesn't matter whether x's type is assignment-compatible with double for this special calling form.

This doesn't work for classdef objects. For example:

octave:1> addpath('~/local/repos/octave-packajoozle/inst')
octave:2> pkg = packajoozle.internal.PkgVer ('financial', '0.5.3')
pkg =
financial 0.5.3

octave:3> p = pkg;
octave:4> p(2) = pkg;
octave:5> p(3) = pkg
p =
financial 0.5.3; financial 0.5.3; financial 0.5.3

octave:6> p(2) = []
error: cannot convert `null_matrix' into `object'
octave:6>

Andrew Janke <apjanke>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:
   
   
Comment:
   

No files currently attached

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by cbm (Posted a comment)
  • -email is unavailable- added by apjanke (Submitted the item)
  •  

    There are 0 votes so far. Votes easily highlight which items people would like to see resolved in priority, independently of the priority of the item set by tracker managers.

    Only project members can vote.

     

     

     

     

    No changes have been made to this item

    Back to the top


    Powered by Savane 3.9