Autocomplete and tab key in PDB

Question

I have been trying to get TAB to do something else than inserting a tab while at the (pdb) prompt.

What I have in mind is triggering autocomplete such as in here or here, but the tab key doesn't do anything else than adding tabs to pdb.

So with:

(pdb)var + tabKeyPressed

I'd want to get:

(pdb)variable

instead of:

(pdb)var[          ]

Answer 1

If you use macOS with NetBSD libedit(default) or your Python is not compiled with GNU readline lib but Net BSD libedit, insert python:bind ^I rl_complete in ~/.editrc. In this case, ^I has two characters.(^ and I)

Also, I found the following strings are possible.

Add one of the strings below into ~/.editrc

# https://github.com/python/cpython/pull/107748#issue-1840209719
# The PR is merged. The tab completion for
# editline(libedit) will be enabled Python 3.13

python:bind "\t" rl_complete
python:bind "\011" rl_complete
python:bind \\t rl_complete
python:bind "   " rl_complete
# " " is a tab.

Also, you have to remove the GNU readline solutions you tried. e.g. some part in ~/.pdbrc(or ./.pdbrc) or rlcompleter of the answer.

Answer 2

Official documents said:

Changed in version 3.3: Tab-completion via the readline module is available for commands and command arguments, e.g. the current global and local names are offered as arguments of the p command.

https://docs.python.org/3/library/pdb.html

So you just using p command:

(Pdb) p var[TAB] # complete global and local names
var1 var2
(Pdb) [TAB] # complete commands
EOF        b          cl         cont       disable    exit       interact   list       next       quit       retval     source     unalias    up         
a          break      clear      continue   display    h          j          ll         p          r          run        step       undisplay  w          
alias      bt         commands   d          down       help       jump       longlist   pp         restart    rv         tbreak     unt        whatis     
args       c          condition  debug      enable     ignore     l          n          q          return     s          u          until      where 

Answer 3

The iPython is third-party solution for this problem. Sometimes you can only rely on vanilla Python. I found 2 solutions for it.

Per-shell solution - usage module 'rlcompleter':

$ python3

Python 3.4.3 (default, Sep 14 2016, 12:36:27) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> import pdb
>>> pdb.set_trace()
--Return--
> <stdin>(1)<module>()->None

# press tab - but nothing
(Pdb) str.
*** SyntaxError: invalid syntax
(Pdb) --KeyboardInterrupt--
(Pdb) c
>>> import rlcompleter
>>> pdb.Pdb.complete=rlcompleter.Completer(locals()).complete
>>> pdb.set_trace()
--Return--
> <stdin>(1)<module>()->None
(Pdb) str.
str.__add__(            str.__getattribute__(   str.__name__            str.__text_signature__  str.isdigit(            str.rfind(
str.__base__(           str.__getitem__(        str.__ne__(             str.__weakrefoffset__   str.isidentifier(       str.rindex(
str.__bases__           str.__getnewargs__(     str.__new__(            str.capitalize(         str.islower(            str.rjust(
str.__basicsize__       str.__gt__(             str.__prepare__(        str.casefold(           str.isnumeric(          str.rpartition(
str.__call__(           str.__hash__(           str.__qualname__        str.center(             str.isprintable(        str.rsplit(
str.__class__(          str.__init__(           str.__reduce__(         str.count(              str.isspace(            str.rstrip(
str.__contains__(       str.__instancecheck__(  str.__reduce_ex__(      str.encode(             str.istitle(            str.split(
str.__delattr__(        str.__itemsize__        str.__repr__(           str.endswith(           str.isupper(            str.splitlines(
str.__dict__            str.__iter__(           str.__rmod__(           str.expandtabs(         str.join(               str.startswith(
str.__dictoffset__      str.__le__(             str.__rmul__(           str.find(               str.ljust(              str.strip(
str.__dir__(            str.__len__(            str.__setattr__(        str.format(             str.lower(              str.swapcase(
str.__doc__             str.__lt__(             str.__sizeof__(         str.format_map(         str.lstrip(             str.title(
str.__eq__(             str.__mod__(            str.__str__(            str.index(              str.maketrans(          str.translate(
str.__flags__           str.__module__          str.__subclasscheck__(  str.isalnum(            str.mro(                str.upper(
str.__format__(         str.__mro__             str.__subclasses__(     str.isalpha(            str.partition(          str.zfill(
str.__ge__(             str.__mul__(            str.__subclasshook__(   str.isdecimal(          str.replace(            
(Pdb) c
>>>

System-wide solution - usage file ~/.pdbrc

$ cat ~/.pdbrc
import rlcompleter
pdb.Pdb.complete=rlcompleter.Completer(locals()).complete
$ python3
Python 3.4.3 (default, Sep 14 2016, 12:36:27) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pdb
>>> pdb.set_trace()
--Return--
> <stdin>(1)<module>()->None
(Pdb) str.
str.__add__(            str.__getattribute__(   str.__name__            str.__text_signature__  str.isdigit(            str.rfind(
str.__base__(           str.__getitem__(        str.__ne__(             str.__weakrefoffset__   str.isidentifier(       str.rindex(
str.__bases__           str.__getnewargs__(     str.__new__(            str.capitalize(         str.islower(            str.rjust(
str.__basicsize__       str.__gt__(             str.__prepare__(        str.casefold(           str.isnumeric(          str.rpartition(
str.__call__(           str.__hash__(           str.__qualname__        str.center(             str.isprintable(        str.rsplit(
str.__class__(          str.__init__(           str.__reduce__(         str.count(              str.isspace(            str.rstrip(
str.__contains__(       str.__instancecheck__(  str.__reduce_ex__(      str.encode(             str.istitle(            str.split(
str.__delattr__(        str.__itemsize__        str.__repr__(           str.endswith(           str.isupper(            str.splitlines(
str.__dict__            str.__iter__(           str.__rmod__(           str.expandtabs(         str.join(               str.startswith(
str.__dictoffset__      str.__le__(             str.__rmul__(           str.find(               str.ljust(              str.strip(
str.__dir__(            str.__len__(            str.__setattr__(        str.format(             str.lower(              str.swapcase(
str.__doc__             str.__lt__(             str.__sizeof__(         str.format_map(         str.lstrip(             str.title(
str.__eq__(             str.__mod__(            str.__str__(            str.index(              str.maketrans(          str.translate(
str.__flags__           str.__module__          str.__subclasscheck__(  str.isalnum(            str.mro(                str.upper(
str.__format__(         str.__mro__             str.__subclasses__(     str.isalpha(            str.partition(          str.zfill(
str.__ge__(             str.__mul__(            str.__subclasshook__(   str.isdecimal(          str.replace(            
(Pdb) c
>>> 

Notes:

1. Tested only on the Python 3.4

2. OS - Linux Mint

3. Based on https://reminiscential.wordpress.com/2009/06/12/python-enable-auto-complete-in-a-pdb-session/

Answer 4

ipdb to the rescue.

ipdb exports functions to access the IPython debugger, which features tab completion, syntax highlighting, better tracebacks, better introspection with the same interface as the pdb module.