[IPython-dev] [Pythonmac-SIG] readline support for OS X Leopard

Boyd Waters bwaters at nrao.edu
Fri Oct 26 21:20:56 EDT 2007

Oops, I spoke too soon when I said that readline support with  
Leopard's Python works for me with IPython.

Many things DO work, but tab-completion does NOT.

I am trying to get tab completion working.

Forget IPython, just try this "unit test" of rlcompleter with the  
Python that ships with Leopard:

See http://docs.python.org/lib/module-rlcompleter.html

  Launch python from a Terminal shell prompt.
  at the prompt, type the following commands:
  import rlcompleter
  import readline
  readline.parse_and_bind("tab: complete")

  Now, try it out: start some input, then hit the Tab key to get some  
possible completions:

  readline. <TAB PRESSED>

  The tab is passed as raw input, and the completer does not give any  

  Tried with both Terminal and xterm.

Reported as Apple Bug # 5563035

I've also asked the IPython devs for help - and volunteered to get  
this resolved somehow for them -- but I don't think it's an IPython  
problem (since you can do this from "raw" interactive python).

Here's hoping...

  - boyd

Boyd Waters
Mac Programmer
National Radio Astronomy Observatory

On Oct 22, 2007, at 12:35 PM, Noah Gift wrote:

> Edward,
> Thanks for the information.  Do you know of a way to get IPython to  
> use edline instead?  IPython is growing in popularity for Python  
> programmers, and it seems like getting a way forward that works with  
> edline makes sense, or maybe I am wrong and people will need to just  
> manually install readline themselves.
> Noah
> On 10/22/07, Edward Moy <emoy at apple.com> wrote:
> On Oct 21, 2007, at 10:51 PM, Noah Gift wrote:
>> I have been getting ready for the official leopard release in a few  
>> days, and have been a bit worried about readline support.  I forgot  
>> what I did to get it to work for IPython, which I absolutely cannot  
>> live without anymore.  Is there a plan for a Leopard binary that  
>> fixes readline, or can I help someone prepare some documentation on  
>> getting readline working properly.  I don't have a lot of time  
>> during the next couple of weeks to get into compile hell, but if  
>> someone has any easy fix to get readline to work, I would greatly  
>> appreciate it.
> The installed version of python on Leopard will actually have  
> readline support turned on by default, but it uses the EditLine  
> (libedit) library, not the GNU Readline (due to licensing reasons).   
> While functionally equivalent, the command syntax is different.   
> From the python(1) man page:
>        The Python inteterpreter supports editing of the current  
> input line and
>        history substitution, similar to facilities found in the Korn  
> shell and
>        the  GNU  Bash shell.  However, rather than being implemented  
> using the
>        GNU Readline library, this Python interpreter  uses  the   
> BSD  EditLine
>        library editline(3) with a GNU Readline emulation layer.
>        The  readline  module  provides the access to the EditLine  
> library, but
>        there are a few major differences compared to a traditional  
> implementa-
>        tion  using  the  Readline  library.   The command language  
> used in the
>        preference files is that of EditLine, as described in  
> editrc(5) and not
>        that   used  by  the  Readline  library.   This  also  means   
> that  the
>        parse_and_bind() routines uses EditLine commands.  And  the   
> preference
>        file itself is ~/.editrc instead of ~/.inputrc.
>        For  example,  the rlcompleter module, which defines a  
> completion func-
>        tion for the  readline  modules,  works  correctly  with   
> the  EditLine
>        libraries, but needs to be initialized somewhat differently:
>               import rlcompleter
>               import readline
>               readline.parse_and_bind ("bind ^I rl_complete")
>        For vi mode, one needs:
>               readline.parse_and_bind("bind -v")
> --------------------------------------------------------------------------
> Edward Moy
> Apple Computer, Inc.
> emoy at apple.com
> _______________________________________________
> Pythonmac-SIG maillist  -  Pythonmac-SIG at python.org
> http://mail.python.org/mailman/listinfo/pythonmac-sig

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