Different behaviour with JRuby-Complete

Ruby JRuby
1

In ruby-processing GitHub - jashkenas/ruby-processing: Code as Art, Art as Code. Processing and Ruby are meant for each other. I have
found two instances where there is a different behaviour when using
regular jruby-1.7.4, or jruby-complete-1.7.4.

  1. When using JRuby-Complete and trying to access a method from an
    abstract java class (which for some reason best known to the java
    library author is ‘protected’) I get method missing (the method is
    public, but is only defined in the abstract class, ho hum). The method
    is ‘visible’ with regular JRuby, and as with regular processing and java
    the method be can used.

  2. The second case is when trying to run processing GLSL shader
    sketches, in this case the JRuby_Complete runs the sketch fine, whereas
    the installed JRuby does not run the sketches. Now this might be similar
    to previous topic (LoadError) Could not load FFI Provider - when using jruby-core jars (1.7.4) - JRuby - Ruby-Forum, but I’m
    not sure how? Both regular JRuby will run OPENGL sketches, which means
    the native JOGL2 binaries can be accessed (they are in jars). Could it
    be
    that I need to explicitly need to do something in the case of regular
    JRuby, that gets done automatically with JRuby-Complete?

2

I would guess the problem here is a difference between using JRuby at
the command line and the jruby-complete jar with a Java command line.

In the first case, JRuby loads itself into the boot classpath, for
startup perf reasons. This can in some cases give it additional
privileges. The latter case loads JRuby as a normal userland class at
the “system” classloader level.

As for loading native libraries, the command-line JRuby rewires the
native loading a little big to get our FFI library to load; this may
cause some native libraries to have problems. Otherwise, it could be a
similar issue, since the boot classloader causes all classes loaded
under it to report a null getClassLoader and some libraries blow up on
that.

If you can provide more concrete examples, ideally with something we
can run and error traces, we can help you work around this or try to
fix it on our end if it represents a JRuby issue.

  • Charlie
3

I know it might be asking a lot, but if you could give ruby-processing a
try, there are the shader examples:-
https://github.com/jashkenas/ruby-processing/tree/master/samples/processing_app/topics/shaders
included with ruby-processing that will not run with an external jruby
and run just fine with the included jruby-complete.

An example of the sketches with method missing (with jruby-complete) are
those that require the fisica library:-
https://github.com/jashkenas/ruby-processing/blob/master/samples/external_library/java_processing/fisica/bubbles.rb
But that is a much bigger ask, unless you’ve already installed
processing, as it requires the fisica library to be installed. To me
this is less interesting, since I would almost expect the method
set_fill to be missing as it is declared public in a lazily protected
abstract class. But it seems regular java processing and the external
jruby are more ‘tolerant’.

4

Here is error message generated with a GLSL shader sketch run with an
external Jruby /usr/bin/jruby -S rp5 run --jruby conway.rb · GitHub

5

Just to be sure, I tested that the correct classpath was being used by
OPENGL sketches whether run using JRuby-Complete or with regular JRuby,
with a simple ‘puts $CLASSPATH’ both correctly pointed to the folder
containing relevant jars (which in processing wrap the native
libraries). So still no further on. I even experimented with this lwgl
app http://www.compoundtheory.com/, which seems to have no difficulty
running shader sketches with regular JRuby.