Readline not detected / not available with ipython

[Eero Aaltonen]

$ jython ipython.py
WARNING: Readline services not available on this platform.
WARNING: The auto-indent feature requires the readline library
Python 2.5.2 (Debian:hg/91332231a448, Apr 28 2013, 20:48:28)

libreadline-java is installed but is apparently not detected.

$ lsb_release -rd
Description: Ubuntu 13.10
Release: 13.10

$ apt-cache policy jython
jython:
  Installed: 2.5.2-2

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: jython 2.5.2-2
ProcVersionSignature: Ubuntu 3.8.0-31.46-generic 3.8.13.8
Uname: Linux 3.8.0-31-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.12.5-0ubuntu2
Architecture: amd64
Date: Thu Oct 24 17:07:25 2013
InstallationDate: Installed on 2013-09-10 (44 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: jython
UpgradeStatus: Upgraded to saucy on 2013-10-23 (0 days ago)

[Eero Aaltonen (ejn)]

The problem seems to be with ipython.

I checked java.library.path and java.class.path, both are ok.

In IPython

>>> from org.gnu.readline import Readline

Works without errors.

[Eero Aaltonen (ejn)]

Re-enactment of what's actually happening inside IPython rlineimpl.py

$ jython
Jython 2.5.2 (Debian:hg/91332231a448, Apr 28 2013, 20:48:28)
[OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_25
Type "help", "copyright", "credits" or "license" for more information.
>>> from readline import *
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/share/jython/Lib/readline.py", line 20, in <module>
    raise ImportError("Cannot access JLineConsole")
ImportError: Cannot access JLineConsole

[Eero Aaltonen (ejn)]

If I pass in the options to jython as

jython -Dpython.console=org.python.core.ReadlineConsole -Dpython.console.readlinelib=GnuReadline ipython.py

I get colors (yay!)
and tab completion (yay! :)

However, it turns out that with this setup, the console has problems echoing (displaying) the line contents and the position of the cursor when
-backspace has been pressed
-left arrow has been pressed

:(

I also saw an extra character popped to the display after using tab completion. The actual parsed line did not however contain the extra displayed character.

[Eero Aaltonen (ejn)]

Source of options
https://wiki.python.org/jython/ConsoleChoices

[Eero Aaltonen (ejn)]

Depends on bug #1254723

[Eero Aaltonen (ejn)]

http://bugs.jython.org/issue1133