bugGNU Octave - Bugs: bug #51470, OF-windows: COM objects do not...


bug #51470: OF-windows: COM objects do not accept method arguments

Submitted by:  Philip Nienhuis <philipnienhuis>
Submitted on:  Sat 15 Jul 2017 10:09:25 AM UTC  
Category:  Octave Forge Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Fixed Assigned to:  None
Originator Name:  Philip Nienhuis Open/Closed:  Closed
Release:  dev Operating System:  Microsoft Windows

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Tue 18 Jul 2017 11:06:16 AM UTC, comment #15: 

Anyway since this is relevant mostly for developers, and not so much for application in user .m file scripts, I think we can do with just com_invoke.

Philip Nienhuis <philipnienhuis>
Project Member
Tue 18 Jul 2017 12:42:25 AM UTC, comment #14: 

general the should still work, the only functions that will get overloaded will be ones that have the com object as the first praramter.

John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 09:20:37 PM UTC, comment #13: 

Sure, but does the builtin methods.m (in scripts/general/) still work for for classdef & Java objects then? I suppose it'll get shadowed.

Since your fix in comment #4, methods.m in core now does at least something for COM objects.
Looking in scripts/general/methods.m, for "general" objects _methods_ is called (in ov-class.cc) that doesn't know about COM objects:

>> methods (app)
Methods for class octave_com_object:
delete   get      invoke   release  set

which are general COM methods (optionally with "com_" prefixed) while the real list is shown (partly) in comment #9.

So I think when the windows package gets loaded it is _methods_() that needs to be overloaded (as we can't add COM-specific stuff to core Octave).

That's as far as my probably oversimplified OOP reasoning goes :-)

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 08:55:01 PM UTC, comment #12: 

Yes does work - I just created a methods.m file

function output = methods (varargin)

  output = com_invoke (varargin{:});


John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 08:48:48 PM UTC, comment #11: 

Yep - close it. I'll take a look and see if methods override is possible.

John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 08:30:28 PM UTC, comment #10: 

BTW shall I set status to "fixed" and close the report?

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 08:29:41 PM UTC, comment #9: 

something like:

>> app = actxserver ("Excel.Application")
app =
<COM object _Application (0x0x2a6aee28)>

>> methods (app)
error: methods: Invalid input argument
error: called from
    methods at line 63 column 5

>> com_invoke (app)
ans =
  [1,1] = ActivateMicrosoftApp
  [2,1] = AddChartAutoFormat
  [3,1] = AddCustomList
  [4,1] = AddRef
  [5,1] = Calculate
  [6,1] = CalculateFull
  [7,1] = CalculateFullRebuild
  [8,1] = CalculateUntilAsyncQueriesDone
  [9,1] = CentimetersToPoints
  [10,1] = CheckAbort
  [11,1] = CheckSpelling
  [12,1] = ConvertFormula
  [13,1] = DDEExecute
  [14,1] = DDEInitiate
  [70,1] = Save
  [71,1] = SaveWorkspace
  [72,1] = SendKeys
  [73,1] = SetDefaultChart
  [74,1] = SharePointVersion
  [75,1] = Support
  [76,1] = Undo
  [77,1] = Union
  [78,1] = Volatile
  [79,1] = Wait
  [80,1] = _Evaluate
  [81,1] = _FindFile
  [82,1] = _MacroOptions
  [83,1] = _Run2
  [84,1] = _WSFunction
  [85,1] = _Wait

I'm not so familiar with OOP; but anyway, what I think is that as methods(app) doesn't work, maybe _COM_.cc can contain a function that overloads or supplements the core Octave methods() function to also work on COM objects?

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 06:52:29 PM UTC, comment #8: 

Can you give an example of what you mean for the overloading?

John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 06:48:55 PM UTC, comment #7: 

already pushed to of-windows

John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 06:37:31 PM UTC, comment #6: 

Thanks, works fine here.
Will you push the fix to the of-windows repo?

BTW I saw that there's no "methods" call for COM objects, yet

com_invoke (<COM-object>)

w/o specifying a method will return a list of methods for that object. Would it be difficult to use this info for making an overloading "methods" function for COM objects?

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 05:06:31 PM UTC, comment #5: 

Wow, that it is so easy.
Thanks, I'll give it a try.
So that'll be windows-1.2.5.soon I guess.

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 04:52:27 PM UTC, comment #4: 
John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 03:30:34 PM UTC, comment #3: 

Yeah looks like it works if I add to the com object:

bool isobject (void) const { return true; }

John Donoghue <lostbard>
Project Member
Mon 17 Jul 2017 03:09:35 PM UTC, comment #2: 

It is possible to work around it using the com_invoke, com_get and com_set functions (much like bug #511532 could be worked around using javaMethod), but that's quite clumsy and does not make for easy to maintain code.

Mike's fix for bug #51152 merely comprised addition of a "isjava(<obj>)" call to an if clause in pt-eval.cc. However that is relatively easy as isjava() is built into core Octave, while an "iscom()" call would have to come from an add-on package.
Maybe COM objects can be masqueraded as general objects?

Philip Nienhuis <philipnienhuis>
Project Member
Mon 17 Jul 2017 01:09:08 PM UTC, comment #1: 

subref function in windows _COM_.cc is giving just a "." as the type - in octave 4.2.1 gives ".("

John Donoghue <lostbard>
Project Member
Sat 15 Jul 2017 10:09:25 AM UTC, original submission:  

I'm a little afraid this is another manifestation of bug #51152

COM objects (ActiveX objects) do not accept arguments, sometimes not even parentheses enclosing the argument(s).
I hit this when investigating io package problems while invoking Excel through ActiveX.  If needed I can show how to reproduce the bug with LibreOffice, but then I'd need to search & undig some old scripts.  But the bug can simply be demonstrated with Notepad.exe as well.

Steps to reproduce:

  • install and load windows package
  • then:

    >> app = actxserver ("WScript.Shell")
    app =

    <COM object IWshShell3 (0x0x11def570)>

    >> app.run ("NOTEPAD.EXE", 3)
    error: com_get: property/method invocation on the COM object failed with error `0x80020003'

Expected result (here with Octave-3.9.0+ I still had installed):

>> app = actxserver ("WScript.Shell")
app =

<COM object IWshShell3 (0x0x8861768)>

>> app.run ("NOTEPAD.EXE", 3)
ans = 0

(the latter hidden behind a full-screen Notepad window. Just use Alt-tab to get to the Octave terminal)
To close the app object, do File | Exit in Notepad and in Octave just:
delete (app);

Philip Nienhuis <philipnienhuis>
Project Member


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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-07-17 philipnienhuis StatusReady For Test => Fixed
        Open/ClosedOpen => Closed
    2017-07-17 philipnienhuis StatusNone => Ready For Test

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