Enable tab-completion in the interactive interpreter by default

http://hg.python.org/cpython/rev/d5ef330bac50

by tshepang • 13 years ago

155 53 13 years ago

hg.python.org

tshepang11• 13 years ago

The related Issue has been open since 2009: http://bugs.python.org/issue5845.

Goranek2• 13 years ago

I always wondered why default interpreter can't be more like bpython.

Good work

thauck• 13 years ago

Some would argue why it can't be more like IPython. :)

But agreed, good work... tab completion is very helpful when learning a language.

Goranek2• 13 years ago

IPython seems to be "too heavy" for me compared to Bpython :)

Bpython is perfect for me.

est• 13 years ago

To use tab completion in earlier Python versions:

    import readline, rlcompleter; readline.parse_and_bind("tab: complete")

gsa• 13 years ago

To make it seamless, put those lines in ~/.pythonrc and add this to your zshrc

    export PYTHONSTARTUP="$HOME/.pythonrc"

niggler• 13 years ago

on OSX you need

    readline.parse_and_bind('bind ^I rl_complete')

alexpopescu2• 13 years ago

I use a combination of all these 3 tricks as I have my dotfiles shared between Mac and Linux.

Basically my pythonstartup.py contains the extra check for os:

    AP_AUTOCOMPLETE=False
    import sys
    try:
        import readline
    except ImportError:
        print "Module readline unavailable"
    else:
      import rlcompleter
      readline.parse_and_bind("tab: complete")
      if sys.platform == 'darwin':
            readline.parse_and_bind("bind ^I rl_complete")
      AP_AUTOCOMPLETE=True

jayflux• 13 years ago

Antoine Pitrou has certainly contributed a lot to CPython.

good work

eliben• 13 years ago

He most certainly did! But did you notice the commit says "original patch by Éric Araujo" ?

obviouslygreen• 13 years ago

Wow, it's about time. It's not that hard to set up tab completion using a startup script, but that always struck me as sort of a backwards thing to have to do every time I set up a new server or workstation.

ak217• 13 years ago

Tangentially related: Shell tab completion for Python programs using argparse: https://github.com/kislyuk/argcomplete

jfb• 13 years ago

Next up: sqlplus.

e1ven• 13 years ago

I know that this is about as useful as the people pointing to ipython, but gqlplus really does do wonders.

wosc• 13 years ago

I've felt that pain too, and heartily recommend rlwrap to lessen it.

dmd• 13 years ago

This is great, but is there any reason whatsoever not to use ipython?

sigzero• 13 years ago

Maybe in a restricted environment where you can't install it?

tshepang11• 13 years ago

I can think of a few:

* awareness

* the official interpreter works quite well already

* yet-another-tool to learn

a3n• 13 years ago

* You're in an interview and they don't have it.

aaronharnly• 13 years ago

I use virtualenv for all projects, and frequently destroy and recreate virtualenvs. iPython takes a good while to install; doing it over and over again in fresh virtualenvs gets to be a chore, so I tend to do it only when I really need it.

I dunno, is there a better way, maybe installing iPython globally, but rewriting the shebang line to use /usr/bin/env python?

tshepang11• 13 years ago

You can always install it directly, and not in a virtualenv. Am I missing something?

e12e• 13 years ago

AFAIK if you're using virtualenvs, you'd best bet would be various approaches to caching/proxying pypi. Won't help if the actual install (compile) times of ipython is a problem though.

takluyver• 13 years ago

A global installation of IPython now recognises if you start it with a virtualenv active, and adds the virtualenv to sys.path so that you can import modules installed there.

It isn't limited to packages in the virtualenv - that is, it always behaves like you created the virtualenv with system-site-packages enabled, because it is importing its own modules from there. But for most interactive use, that's not a problem.

MostAwesomeDude• 13 years ago

There are two reasons that I can think of that I have experienced. First, IPython simply doesn't behave like standard Python; you can have very obscure corner-case bugs in otherwise-normal code because of its magic. Second, if you're using PyPy, you don't get to use IPython.

Edit: I meant that PyPy isn't compatible with most of the things people use IPython for, like Numpy and Scipy, not that IPython's shell doesn't work on PyPy. Sorry.

freyrs3• 13 years ago

The command line IPython does work with the PyPy interpreter.

gjhiggins• 13 years ago

The ipython interaction trace seems to run counter to the grain of doctest/docstring. I frequently copy and paste standard interactive sessions into a file to act as docstring exemplars or immediate doctest content for cross-platform/cross-version compatibility checking. I couldn't see how to do that with published ipython session output. Is it just a matter of changing the ipython prompt or is it a more fundamental issue?

tshepang11• 13 years ago

It's also ugly when copy-pasted, which does not stop people exposing such ugliness on sites like Stack Overflow.

fperez_org• 13 years ago

You can always use `%doctest_mode` to toggle back and forth between IPython-style prompts and `>>>` ones (along with changing exception mode to be more standard-looking).

cpdean• 13 years ago

Yeah, iPython already has tab completion, and everyone is still free to use it. It has plenty of great additional features, too!

Everyone is talking about reasons why using iPython can be impractical, or cumbersome/not-possible to install, but the important thing is that the default experience should strive to be the best experience.

Python has a pretty good standard library, and a pretty good batteries-included toolset, but talk to anyone who's experienced in it and you'll hear about all the Best Tools you have to install in order to be up to par: pip, virtualenv, ipython, third-party libraries to supplement what you want to do (requests, *-parse...).

When the community agrees that there are certain extras that are all good to install, it shows that the features they offer should probably be provided by default. I like Python, and I want Python to provide the best experience by default.

tshepang11• 13 years ago

People are working (or planning to work) on some of those:

* pip (sort of): http://www.python.org/dev/peps/pep-0439/

* virtualenv: already in Python 3.3

* requests: http://kushaldas.in/posts/notes-from-language-summit-at-pyco...

As for IPython, many would agree it's not suitable for inclusion, which is not necessarily a bad thing. That does not stop anyone from stealing some of its features for inclusion in the default interactive interpreter though.

scott_karana• 13 years ago

It's annoying to have to install Conda for a single program.

oellegaard• 13 years ago

Will this be on 2.7.x or just 3.x?

tshepang11• 13 years ago

3.4, early next year http://www.python.org/dev/peps/pep-0429

circuiter• 13 years ago

Is there anything that would prevent this from being backported to 2.x.x ?

spicavigo• 13 years ago

I don't remember the last time I used anything except iPython. I use EC2 a lot, and the first thing I do after firing an instance is install ipython, even if I don't intend to use the instance for python related stuff at all.

digisign• 13 years ago

I've always wondered why so many of these usability niceties have been available yet neglected soooo long, while the language as a whole has progressed so much? There are plenty more of these, like interpreter history and adding pip to the stdlib.

On Windows it's even worse, newbies have to figure out how to get it in their path and hunt-down important libraries.

tshepang11• 13 years ago

The mystery goes away once you start reading python-dev and watching bugs.python.org... people find it hard to agree on the right way to do things. It takes a lot of energy for the bigger changes to go in, and many of those with the energy are busy working on other things, while the Issues rot. CPython needs more contributors (as does so many volunteer software projects).

mixmastamyk2• 13 years ago

Hmm, they might take a cue from the Active State distribution, who has done a lot of things right.

mixmastamyk2• 13 years ago

BTW, are you implying/do you think I could get some of these in with some enthusiasm and a bit of work (given they've been implemented for a decade).

Camillo• 13 years ago

One problem with tab completion is that you can no longer paste tab-indented snippets into the intepreter, or use tab to indent code you're typing. I put the following in my python startup file to fix the issue:

    import readline, rlcompleter
    readline.parse_and_bind("tab: complete")
    readline.parse_and_bind('bind ^I rl_complete')
    
    class MyCompleter(rlcompleter.Completer):
    	def complete(self, text, state):
    		if text.lstrip() == '':
    			if state == 0:
    				return text + '\t'
    			else:
    				return None
    		else:
    			return rlcompleter.Completer.complete(self, text, state)
    
    readline.set_completer(MyCompleter().complete)

alexpopescu2• 13 years ago

Niiiice!

Enable tab-completion in the interactive interpreter by default

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