build python against libedit instead of readline

[jmroot (Joshua Root)]

GNU readline is licensed under GPL-3+, whereas libedit is BSD. Using libedit will therefore make the binary distribution situation easier. This is actually the default configuration on OS X for upstream anyway, as Apple's libreadline is a link to libedit.

Should just be a matter of patching the configure script to change -lreadline to -ledit and readline/readline.h to editline/readline.h.

[ned-deily (Ned Deily)]

Note that there was feature code added to Python to support using libedit instead of readline. That feature code was added to python26, python27, and python32 but not other versions; see ​http://bugs.python.org/issue6877

[jmroot (Joshua Root)]

Turns out the incompatibility is fixed in the version of libedit we now install, which means it actually crashes unless we revert the upstream python patch.

Also, readline is in a separate port for python24, so this is not a big deal for that version.

[jmroot (Joshua Root)]

r86868

[ned-deily (Ned Deily)]

Note that linking with libedit instead of GNU readline introduces potential user incompatibilities. As noted in the ​docs for the Python readline module , the configuration file commands for libedit are different than readline. For example, if you have a PYTHONSTARTUP file set up to enable tab completion in the Python interactive interpreter, the directives have to be changed or be conditional based on which library is used or directives have to be added to .editrc (the libedit defaults file). Here's an example:

    import rlcompleter
    if 'libedit' in readline.__doc__:
        readline.parse_and_bind("bind ^I rl_complete")
    else:  # GNU readline format
        readline.parse_and_bind("tab: complete")

Also, py27-ipython and py32-ipython (at least) complain when running with a python linked with libedit:

/macports/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/utils/rlineimpl.py:96:
RuntimeWarning: Leopard libedit detected - readline will not be well behaved including some crashes on tab completion, and
incorrect history navigation. It is highly recommended that you install readline, which is easy_installable with: 'easy_install readline'
  RuntimeWarning)

[cdeil (Christoph Deil)]

I have the same problem with ipython. Actually the ipython prompt is broken:

$ /opt/local/bin/ipython-2.6 
/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/IPython/utils/rlineimpl.py:96: RuntimeWarning: Leopard libedit detected - readline will not be well behaved including some crashes on tab completion, and incorrect history navigation. It is highly recommended that you install readline, which is easy_installable with: 'easy_install readline'
  RuntimeWarning)
Python 2.6.7 (r267:88850, Nov  8 2011, 12:13:06) 
Type "copyright", "credits" or "license" for more information.

IPython 0.11 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.
34In[1;3[0;34][0^D

Same warning and broken prompt whether I use ipython from MacPorts of the git master.

Any workaround / fix from this from the Macports or Ipython side? Should I file a new ticket?

[cdeil (Christoph Deil)]

Cc Me!

[spork-macports@…]

Cc Me!

[jmroot (Joshua Root)]

See #31938 regarding ipython. Basically you can just install the appropriate py*-readline port.