Re: Problems with unwanted auto-boxing Java objects in 3.7.1+

[Philip Nienhuis]

Hi Michael,

Thanks for answering. I've cc'd the maintainers list, OK?
pls read on:

Michael Goffioul wrote:
> On Fri, Jan 25, 2013 at 5:09 PM, Michael Goffioul
> <address@hidden <mailto:address@hidden>> wrote:
>
>     On Fri, Jan 25, 2013 at 5:05 PM, Michael Goffioul
>     <address@hidden <mailto:address@hidden>> wrote:
>
>         On Fri, Jan 25, 2013 at 4:46 PM, PhilipNienhuis
>         <address@hidden <mailto:address@hidden>> wrote:
>
>             (ref:
>             
> https://mailman.cae.wisc.edu/pipermail/octave-maintainers/2012-December/031429.html)
>
>             While trying to convert the io package spreadsheet scripts
>             to work with the
>             new built-in Java interface in 3.7.1+, I hit a bit of a
>             showstopper with the
>             UNO interface (LibreOffice/OpenOffice.org) scripts:
>
>             After a bit of fiddling with various LibreOffice Java calls
>             and objects, the
>             following call is used in an io package script meant for
>             opening a
>             LibreOffice spreadsheet file:
>
>             xComp = aLoader.loadComponentFromURL
>             ("private:factory/scalc", "_blank", 0,
>             lProps);
>
>             (where aLoader is a <java_object> of class $Proxy3 in
>             3.7.1+, or octave_java
>             class in 3.6.4-rc1.)
>
>             In 3.6.4-rc1 with the OF Java package, the above call
>             returns xComp as a
>             Java object (class octave_java).
>             However, in 3.7.1+ xComp now gets casted to a plain Octave
>             (empty) double.
>             Doubles are not amenable for the next Java method call in line:
>             xSpdoc = xComp.queryInterface (unotmp)
>
>             Trying to rewrite the offending line into:
>
>             xComp = javaMethod ("loadComponentFromURL", aLoader, ...
>             "private:factory/scalc", "_blank", 0, lProps)
>
>             doesn't help: still I get an empty double.
>
>             How can the proper class of xComp be retained / obtained?
>             or, IOW, is there
>             a way to avoid auto-boxing of Java Objects?
>
>             Thanks,
>
>             Philip
>
>
>         What is the java returned type of  loadComponentFromURL?

xComp (the result of aLoader.loadComponentFromURL (<args>) is empty 
double ( 1x1 [] ) in 3.7.1+, but class <octave_java> in stable Octave 
with OF Java package: <Java object: $Proxy4>

For how it looks in Windows (in Octave3.6.2MSVC2010) see below.

All Java objects created by the Libre/Open-Office UNO Java classes are 
of the <octave_java> class, or $Proxy<some_number> (an OpenOffice.org 
idiosyncray) for stable Octave versions with OF Java package.

>     If this [1] is the function we're talking about, I suspect it's
>     actually returning NULL and you get an empty matrix on the octave
>     side. This would then indicate that the method fail. Maybe the
>     problem is due to incorrectly casting the method arguments?

You may be right here, but it would be 'casting' from Octave to Java.

All I can see is that the method in question fails (and indeed, probably 
returns NULL) in Octave 3.7.1+ while it does work OK in 3.6.4.-rc1.
So, something did change when the Java package was absorbed in core Octave.

I did some more investigating; it turns out that creating a new file 
fails, but opening an existing spreadsheet succeeds, however the latter 
with a visible OOo/LO spreadsheet window (should be hidden).
I suspect the latter happens because the Java 1x1 array lProps (the 4th 
argument to the failing method) gets mangled somehow. But that doesn't 
explain why creating a new file fails completely, as both calls to 
aLoader.loadComponentFromURL (i.e., creating/opening a file) only differ 
in the first filename argument.

So far my interpretation is that currently Octave somehow has changed 
the way it conveys Java objects to Java. Whether it has always been 
wrong (in the OF Java package) and is "correct" (ML compatible?) now, or 
the other way round, I can only guess.

> Sorry, I forgot the link:
>
> [1]
> http://www.openoffice.org/api/docs/common/ref/com/sun/star/frame/XComponentLoader.html

Yep this is the class. The method is 'loadComponentFromURL()'

Debugging the inner workings of the XComponentLoader class is beyond me.
Replacing the third argument to loadComponentFromURL() (currently 0) 
with a java.lang.Long didn't make any difference (neither in stable 
Octave with OF Java nor in Octave 3.7.1+).

Perhaps a bit prematurely I'll attach the io package function in 
question, __UNO_spsh_open__.m, most of all just to provide some insight 
in the various Java method calls.

After adding .jars to the javaclasspath by invoking
chk_spreadsheet_support ('', 3, '/full/path/to/libreoffice')
it can be run simply in a stable Octave with Java and io package loaded 
using the following commands:

xls.changed = 0;
dbstop __UNO_spsh_open__ 66
xls = __UNO_spsh_open__ (xls, 3, "io-test.xls", 0)

When interrupted at L.66 and dbnext'd until L.72, "whos" gives:

   Attr Name            Size                     Bytes  Class
   ==== ====            ====                     =====  =====
        aLoader         1x1                          0  octave_java
  a     argn            4x13                        52  char
    f   filename        1x48                        48  char
        flen            1x1                          8  double
        fname           1x41                        41  char
        lProp           1x1                          0  octave_java
        lProps          1x1                          0  octave_java
        oDesktop        1x1                          0  octave_java
        tmp             1x12                        41  cell
        unotmp          1x1                          0  octave_java
        xComp           1x1                          0  octave_java
        xContext        1x1                          0  octave_java
        xMCF            1x1                          0  octave_java
        xSpdoc          1x1                          0  octave_java
    f   xls             1x1                          8  struct
    f   xlssupport      1x1                          8  double
    f   xwrite          1x1                          8  double

Philip