Re: usejava.m

[Philip Nienhuis]

Rik wrote:
>   On 02/04/2012 08:54 AM, address@hidden wrote:
>
> >  Date: Fri, 3 Feb 2012 15:29:06 -0800 (PST)
> >  From: PhilipNienhuis <address@hidden>
> >  To: address@hidden
> >  Subject: usejava function
> >  Message-ID: <address@hidden>
>
> 2/6/12
>
> Philip,
>
> I added the function usejava(). It is entirely a stub and returns false
> since core Octave does not support Java. It was mainly a gesture towards
> compatibility. My guess is that most Matlab programs either use Java
> features or don't use Java features, but probably very few of them have
> coded up tests to check with usejava() and then implement an alternative.
>
> If you want to improve the function please go ahead. I think either
> approach you outlined is fine. I had been assuming something like your
> second approach which is a C++/inheritance way of thinking. In this way
> of thinking, the core defines a function but the behavior can be
> overloaded or modified by a subclass. In this case, core Octave does not
> support Java but if someone has installed a package, like the
> Octave-Forge one, that did add support for some functionality then it
> could overload usejava and tell users which features it supported.
>
> I do know how freaked people get when they see a warning message so if
> you want to adopt approach #1 that is also good.

OK, for approach #1 a changeset is attached.

I looked at the tests but it is a bit beyond me to devise a reliable 
test that would invoke the Java package.
As it stands, the tests would only be usable in a "make check" session 
right after building Octave.
But fortunately, the "desktop" feature test should always return false 
anyway as Octave doesn't have a Java-based desktop GUI.

Transcript from an Octave-3.6.0 session with openjdk:

========================================================
address@hidden ~]$ ls /usr/lib/jvm
java@        java-1.6.0-openjdk@          java-openjdk@  jre-1.6.0@ 
     jre-openjdk@
java-1.6.0@  java-1.6.0-openjdk-1.6.0.0/  jre@           jre-1.6.0-openjdk@
address@hidden ~]$ octave
GNU Octave, version 3.6.0
Copyright (C) 2012 John W. Eaton and others.
This is free software; see the source code for copying conditions.
There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.

Octave was configured for "i686-pc-linux-gnu".

Additional information about Octave is available at http://www.octave.org.

Please contribute if you find this software useful.
For more information, visit http://www.octave.org/help-wanted.html

Read http://www.octave.org/bugs.html to learn how to submit bug reports.

For information about changes from previous versions, type `news'.

octave:1> pkg list
Package Name  | Version | Installation directory
--------------+---------+-----------------------
          io *|  1.0.16 | /usr/local/share/octave/packages/io-1.0.16
        java *|   1.2.8 | /usr/local/share/octave/packages/java-1.2.8
octave:2> usejava ("awt")
ans =  1
octave:3> usejava ("desktop")
ans = 0
octave:4> usejava ("swing")
ans =  1
octave:5> usejava ("jvm")
ans =  1
octave:6> pkg unload java
octave:7> usejava ("awt")
ans = 0
octave:8> usejava ("swing")
ans = 0
octave:9> usejava ("desktop")
ans = 0
octave:10> usejava ("jvm")
ans = 0
octave:11>
========================================================

Philip

usejava.patch
Description: application/download