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cmd module tab misbehavior #53279

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cmd module tab misbehavior#53279
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ronaldoussoren
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OS-mactype-bugAn unexpected behavior, bug, or error

Description

@slcott
slcott
mannequin
opened on Jun 19, 2010
BPO 9033
Nosy @ronaldoussoren, @ned-deily, @merwok, @zvezdan, @boompig
Files
  • cmd.patch
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/ronaldoussoren'
closed_at = None
created_at = <Date 2010-06-19.15:10:14.122>
labels = ['OS-mac', 'type-bug']
title = 'cmd module tab misbehavior'
updated_at = <Date 2018-01-17.22:24:11.948>
user = 'https://bugs.python.org/slcott'

    bugs.python.org fields:

    activity = <Date 2018-01-17.22:24:11.948>
actor = 'boompig'
assignee = 'ronaldoussoren'
closed = False
closed_date = None
closer = None
components = ['macOS']
creation = <Date 2010-06-19.15:10:14.122>
creator = 'slcott'
dependencies = []
files = ['17782']
hgrepos = []
issue_num = 9033
keywords = ['patch']
message_count = 13.0
messages = ['108185', '108196', '108200', '108353', '108379', '108380', '108381', '108392', '108792', '109732', '109746', '193157', '310213']
nosy_count = 7.0
nosy_names = ['ronaldoussoren', 'ned.deily', 'eric.araujo', 'zvezdan', 'l0nwlf', 'slcott', 'boompig']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue9033'
versions = ['Python 3.6']

    Activity

    1. slcott commented on Jun 19, 2010

      @slcott
      slcottmannequin
      on Jun 19, 2010
      MannequinAuthor

      noticed that cmd module does not perform completion using TAB on a macintosh properly. instead, the TAB key just places several blank spaces and moves the cursor forward. what it should do is retrieve a list of possibilities for completing a command.

    2. slcott
      assigned
      ronaldoussoren
      on Jun 19, 2010
    3. slcott
      added
      OS-mac
      type-bugAn unexpected behavior, bug, or error
      on Jun 19, 2010

    4. merwok commented on Jun 19, 2010

      @merwok
      merwok
      on Jun 19, 2010
      Member

      Thanks for your report. Does the readline module work at all?

      2.5 is unsupported now; can you test your code with 2.7, the next stable version?

    5. l0nwlf commented on Jun 19, 2010

      @l0nwlf
      l0nwlfmannequin
      on Jun 19, 2010
      Mannequin

      It seems readline module is not installed on your system.
      Quoting Ned Deily's comment from bpo-8365 which will most probably solve your issue:
      "bpo-6877 (and subsequent fixes in bpo-8066) allows the Python readline module to be built and linked with the OS X editline (libedit) library rather than with the GNU readline library (which is not included with OS X). However, the libedit included in versions of OS X prior to 10.5 is considered too broken to use here.

      By default, if you do not specify an --with-universal-archs other than "32-bit" to configure or if you do not explicitly set MACOSX_DEPLOYMENT_TARGET to another value, configure defaults to using "10.4" (or earlier) so the building of the readline module is skipped. You can check this:

      >>> from distutils.sysconfig import get_config_var 
>>> get_config_var('MACOSX_DEPLOYMENT_TARGET')
'10.4'

      (Whether this is the best default is another question.)

      As it stands, to be able to build the readline module, either:

      (1) supply the GNU readline library as a local library, or

      (2) ensure you are building with a deployment target of at least 10.5. For example:

      ./configure MACOSX_DEPLOYMENT_TARGET=10.6 ; make

      Also note that option (2) is not available for 3.1.x since the changes to support editline/libedit were not ported to it; they are, however, in 2.6.5, 2.7 (trunk), and 3.2 (py3k)"

    6. ronaldoussoren commented on Jun 22, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jun 22, 2010
      Contributor

      scott:

      • Which OSX version are you using?

      • Which Python are you using?

        • What is the value of sys.prefix?
        • How did you install it?

      • Does 'import readline' work?

    7. ronaldoussoren commented on Jun 22, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jun 22, 2010
      Contributor

      Reaction from scot w.r.t. my questions:

      os x 10.5.8

      python 2.5.1

      /System/Library/Frameworks/Python.framework/Versions/2.5

      came default with system

      i'm going to try activestate python 2.6 and see if that solves the problem.

      import readline does work

    8. ronaldoussoren commented on Jun 22, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jun 22, 2010
      Contributor

      Some notes: The system python on OSX 10.5 and 10.6 is linked to libedit, not GNU readline, and doesn't seem to contain patches that convert stdlib usage of readline APIs to the correct way to bind keystrokes to action with libedit.

      This results in failure to use libedit at all.

      AFAIK this also affects the generic stdlib when linking libedit, which is supported in 2.6.5, 2.7 and 3.2. Therefore adding more versions.

    9. ronaldoussoren commented on Jun 22, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jun 22, 2010
      Contributor

      This (untested) patch should fix the issue for the cmd module:

      +++ Lib/cmd.py	(working copy)
@@ -112,7 +112,18 @@
                 import readline
                 self.old_completer = readline.get_completer()
                 readline.set_completer(self.complete)
-                readline.parse_and_bind(self.completekey+": complete")
+
+                if 'libedit' in readline.__doc__:
+                    # readline linked to BSD libedit
+                    if self.completekey == 'tab':
+                        key = '^I'
+                    else:
+                        key = self.completekey
+                    readline.parse_and_bind("bind %s rl_complete"%(key,))
+
+                else:
+                    # readline linked to the real readline
+                    readline.parse_and_bind(self.completekey+": complete")
             except ImportError:
                 pass
         try:

    10. l0nwlf commented on Jun 22, 2010

      @l0nwlf
      l0nwlfmannequin
      on Jun 22, 2010
      Mannequin

      Tested the patch and it works for trunk and python3.2 alpha.
      Without adding SDK flag with configure readline module failed to build.

      Python build finished, but the necessary bits to build these modules were not found:
      _gdbm ossaudiodev readline
      spwd

      However for cmd module, tab completion and history(up|down arrow) worked fine.

    11. ronaldoussoren commented on Jun 27, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jun 27, 2010
      Contributor

      The attached patch is a workaround for the issue, but isn't someone I'd want to commit without some serious cleanup.

      As I noted when support for linking with libedit was merged it would be better to add a translation layer that translates GNU readline configuration lines to BSD libedit ones.

    12. zvezdan commented on Jul 9, 2010

      @zvezdan
      zvezdanmannequin
      on Jul 9, 2010
      Mannequin

      Does a translation really need to be in Python?

      I use .editrc file in my home directory with this content:

      python:bind ^I rl_complete

      and everything works fine.

    13. ronaldoussoren commented on Jul 9, 2010

      @ronaldoussoren
      ronaldoussoren
      on Jul 9, 2010
      Contributor

      We either have to add some translation, or tweak parts of python:

      • the cmd module needs to learn how to configure libedit when
        the readline extension was linked to libedit

      • the rlcompleter documentation needs to be updated to do the same

      And that's just the stdlib. IIRC ipython contains code that uses libedit
      style configuration instead of readline when using /usr/bin/python on OSX, and there are probably other.

      IMHO the current behavior is confusing: the module is named readline, but sometimes uses libedit behavior. At least I ensured that the usage of libedit can be detected by introspecting readline.__doc__.

      A basic translator shouldn't be that hard...

    14. ronaldoussoren commented on Jul 16, 2013

      @ronaldoussoren
      ronaldoussoren
      on Jul 16, 2013
      Contributor

      I no longer particularly like my patch, although something needs to be done. The easiest way forward is likely a (private) helper function in the readline module that can translate simple readline configuration strings to something that libedit understands and use that in the stdlib where readline bindings are replaced (but of course not for reading ~/.inputrc).

      Comparing the libedit <http://linux.die.net/man/5/editrc\> and readline <http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC9\> configuration languages makes is clear that it is not possible to fully translate a readline configuration in a libedit one, but basic conifguration like setting up key-bindings should be easy enough.

    15. boompig commented on Jan 17, 2018

      @boompig
      boompigmannequin
      on Jan 17, 2018
      Mannequin

      I can confirm this behaviour for python 3.6.0 on Mac OS X 10.12.6

    16. ezio-melotti
      transferred this issue fromon Apr 10, 2022

    17. ronaldoussoren commented on Nov 22, 2022

      @ronaldoussoren
      ronaldoussoren
      on Nov 22, 2022
      Contributor

      Issue is still present, although command completion does work in an interactive shell (that is, start cmdloop() from the REPL.

      Also: site.py contains code that similar to my "cmd.patch", I intend to create a PR based on it.

    18. encukou commented on Jun 17, 2024

      @encukou
      encukou
      on Jun 17, 2024
      Member

      This was fixed in #107748, for Python 3.13. From my Mac:

      $ PYTHON_BASIC_REPL=1 ./python.exe
Python 3.14.0a0 (heads/main:2c7209a3bdf, Jun 17 2024, 17:10:56) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> i<tab><tab>
id(         if          import      in          input(      int(        is          isinstance( issubclass( iter(      
>>> import readline
>>> readline.<tab><tab>
readline.add_history(                         readline.read_history_file(                  
readline.backend                              readline.read_init_file(                     
readline.clear_history()                      readline.redisplay()                         
[... several lines omitted ...]                  
>>> readline.backend
'editline'

      It's a new feature, so it's not backported. But, in Python 3.11 tab completion should work if you install readline and build with ./configure --with-readline=readline.

    19. encukou
      closed this as completedon Jun 17, 2024
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