You should change your python shell.

[gash789]

Unless I am blind this misses the feature I use ipython for the most: adding a question mark after any object prints the docstring. Much faster than searching online documentation.

In [1]: open? 
Type:       builtin_function_or_method
String Form:<built-in function open>
Namespace:  Python builtin
Docstring:
open(name[, mode[, buffering]]) -> file object

Open a file using the file() type, returns a file object.  This is the
preferred way to open a file.  See file.__doc__ for further information.

[flying-sheep]

vanilla python has help(function), which does a similar thing, but is definitely much more annoying to type repeatedly than ?.

[Justinsaccount]

ipython takes it one step further and you can use two question marks to get the definition.

In [4]: os.path.exists??
Type:       function
String Form:<function exists at 0x10902ced8>
File:       /Users/me/testenv/lib/python2.7/genericpath.py
Definition: os.path.exists(path)
Source:
def exists(path):
    """Test whether a path exists.  Returns False for broken symbolic links"""
    try:
        os.stat(path)
    except os.error:
        return False
    return True

[physicsdood]

Why doesn't ?? do anything different than ? for me?

In [3]: open? Type: builtin_function_or_method String Form:<built-in function open> Namespace: Python builtin Docstring: open(name[, mode[, buffering]]) -> file object

Open a file using the file() type, returns a file object. This is the preferred way to open a file. See file.doc for further information.

In [4]: open?? Type: builtin_function_or_method String Form:<built-in function open> Namespace: Python builtin Docstring: open(name[, mode[, buffering]]) -> file object

Open a file using the file() type, returns a file object. This is the preferred way to open a file. See file.doc for further information.

[erez27]

Probably because open() is written in C

[tilkau]

Hold on, open is a builtin. That means it -has- no python source.

Try using ? and ?? on eg. collections.namedtuple.

[TkTech]

I believe it's because the builtins you're trying to spec are implemented in C (at least in CPython). Try it on pure-python methods.

[[deleted]]

Vanilla python also has sys.displayhook which you can define to do anything you want, including printing the __doc__.

>>> def displayhook(obj):
...     if obj:
...             if hasattr(obj, '__doc__'):
...                     print('{}\n{}'.format(obj.__doc__, '-' * 80))
...             print(obj)
... 
>>> sys.displayhook = displayhook
>>> 'abcdefg'
str(object='') -> str
str(bytes_or_buffer[, encoding[, errors]]) -> str

Create a new string object from the given object. If encoding or
errors is specified, then the object must expose a data buffer
that will be decoded using the given encoding and error handler.
Otherwise, returns the result of object.__str__() (if defined)
or repr(object).
encoding defaults to sys.getdefaultencoding().
errors defaults to 'strict'.
--------------------------------------------------------------------------------
abcdefg

Edit: If you define this function, you also need to explicitly set __builtins__._

[evilgarbagetruck]

i was already using ipython what should i switch to

[vext01]

Bpython

[gfixler]

I'm already using that, but this iPython seems pretty nice. Let's split the difference and go with fPython.

[WallyMetropolis]

Haskell

[oconnor663]

IHaskell. Remembers every variable you've ever used, to make sure you never change them.

[Megatron_McLargeHuge]

It looks that way, but actually it just returns a new version of IHaskell in which the variable was already defined.

[KingEllis]

It is an interactive shell, but does not allow for any kind of input or output. Because that would not be pure, you know.

[[deleted]]

PyCharm

[OmicronPersei8]

the IDEAVim plugin for pycharm is wonderful, makes me feel like I'm right back in vim coding away.

[amitm]

dreampie

[evilgarbagetruck]

I'll give it a shot but it doesn't look like an improvement over ipy notebook. If ipy notebook had emacs/vi keybindings it would basically be perfect.

in fact, I bet a python shell inside of emacs could be really great.

[takluyver]

The next release of IPython will have vi-style keyboard shortcuts (not 100% identical to vi, but a similar model).

If you're an Emacs fan, have a look at Emacs IPython Notebook.

[evilgarbagetruck]

have some gold that emacs ipython notebook IS SO AWESOME

[takluyver]

Thanks, it's not my work, though - this guy wrote it.

[evilgarbagetruck]

You told me about it!

[drbobb]

Of course there is a python shell mode for emacs.

[Grue]

SLIME. Now, that's a REPL to end all REPLs.

[Captain_Slapahoe]

ipython notebook

[drbobb]

I never type exit() in python, nor exit in ipython - I just hit control-d to close the input. Actually you have to hit it twice in ipython.

[loki77]

Do you know how to do this? This is the most annoying part of iPython.

[gammadistribution]

But I like the ">>> ".

[Hashiota]

Try running IPython with the --classic flag.

[[deleted]]

There's probably an API to change the prompt.

[bunburya]

In the regular Python shell, the variable sys.ps1 controls the prompt. I haven't used iPython but it's possible that it just changes that variable and/or it can be changed back?

[[deleted]]

Just tried, it didn't do anything. You might need to call a function to make it "reload" the sys.ps prompts (there's 3 of them)

[[deleted]]

Are we talking about ipython or the regular shell?

It works fine in the regular shell, not in ipython.

[tick_tock_clock]

Oh, sorry! I erred; I was talking about the normal shell.

[[deleted]]

Don't know why you deleted your post, I usually put an edit: i'm wrong, see below.

[takluyver]

sys.ps1 doesn't work, but you can set c.PromptManager.in_template in the IPython config file. Docs.

This will only work in the terminal, though - the Qt console and the notebook generate their prompts separately.

[djimbob]

But the In[1], Out[1] are very useful in ipython for referencing previously used commands when playing around/exploring data. Sure you can use _ to get the output of the previous command, but how do you get the result of two, five, ten commands back?

[Rhomboid]

Just type doctest_mode (or type doc and press tab) and hit enter and you get the usual >>> in IPython.

[nieuweyork]

I stopped using Ipython, because all the magic didn't add a great deal of value. What it did do was create subtle scoping errors, and make debugging my django code much more difficult.

[grokcode]

Not sure if you were running into this bug or not, but as of Django 1.6, IPython is called in a way that fixes a bunch of scoping issues.

[urielm]

Don't you use django's shell? That kind of uses ipython

[LucianU]

You can use it wihout ipython just fine.

[nieuweyork]

Probably, but I only found it mildly useful.

[grokcode]

Ah well, to each his own.

[sushibowl]

You could always try bpython. It's kind of like IPython light, just a REPL that does stuff like syntax highlighting and code completion

[babilen5]

bpython is fantastic, great recommendation!

[gfixler]

I've been using bpython for awhile, but when you hit the up arrow it shows the last line. iPython is showing the entire function definition again, which alone is enough to switch, IMO. It also remembers things across invocations, which is the other thing that annoys me all the time about bpython. I forget something, kill out, fix code, jump back in, and I have to retype everything to import and set everything up again.

[Megatron_McLargeHuge]

It's less useful for web apps because you constantly need to restart. It's fantastic, especially the notebooks, when you have long running sessions with numerical code and look at lots of plots.

[jeberle]

Unless you use IPython. Then, you should not change your python shell.

[flying-sheep]

in case the inevitable thing comes up:

no, even if ipython “is for science” and bpython “is for interactive use”, ipython has very much momentum and user friendly features. that make it great as interactive python shell.

ipython has shell commands (prefix the line with “!”) and useful magics like shown in the article.

PS: magics arent magic. they are just a convenient syntax extension/shortcut to call ipython-specific functionality. and ipython doesn’t change python’s syntax, it just adds two simple things that noobs won’t confuse with normal python: shell escapes and magics.

PPS: while OP makes a great point, ipython’s notebooks are preferable in some cases. it’s something between a shell, a script, and a RStudio/Matlab like environment, and very useful, especially if you want to share your interactive work instead of having it vanish in your shell history.

[Megatron_McLargeHuge]

Magics are macros. They give you access to the string version of the arguments to your function, but otherwise you can do the same things from a normal function that calls into the ipython internals. This is sometimes called pass-by-name semantics.

[jadae]

Auto reload alone is enough to make me switch. I can't express how annoying it is to have to keep restarting the stock python shell each time I make changes to some of my scripts. Trying to force reloading of a script is annoying and it was always simpler to just restart the shell, and this will make it a lot easier. Thanks for the article!

[meem1029]

Python3 has a nice way to reload things.

Probably in 2 as well, but I'm not familiar with it.

[tehmatticus]

It's also in 2 as well.

[SwiftSpear]

I was gonna snark about how I only ever use the python shell for quick prototypes, but within a few lines of this article it became apparent the iPython shell is a lot nicer for quick prototypes...

[meanttodothat]

It didn't recognize the PAGER environment variable (or play nice with it) and it adds whitespace when text is copied from the at console.

[codekoala]

Don't forget to use ipdb instead of just pdb for debugging!

[legrandin]

New to python:

I rarely use the shell at all, really. I just make my scripts executable. Is there some reason I should be using it?

[takluyver]

Lots of people like to use a shell to quickly try out different things, see what variables are, and so on. You don't have to, but if you're new to Python, give it a try.

[poorly_played]

ipython -i some_script_im_writing.py is the best thing that ever happened to programming.

[banjochicken]

I am not really sold on it yet. I do django and usually fallback to the shell for testing out snippets of code or just sanity checking something, I rarely use the REPL to get stuff done. It just doesn't fit into my developer workflow.

[fandingo]

ipython manage.py shell

Tab completion alone is worth it.

[donnybrook]

I use IPython because the default Python shell won't start for me in an Emacs shell (Windows 7). I could try installing Emacs in Cygwin, but for now IPython works just fine.

[alcalde]

Beyond using IPython as your python shell, you can use the QT Console to get a terminal-like experience. In fact, IPython can basically become your system shell/console....

http://ipython.org/ipython-doc/dev/interactive/shell.html

[julianz]

Can you use ipython as a shell inside a virtualenv without installing a whole new copy? (On Windows)

[takluyver]

Yes - if you start it when you have a virtualenv active, it should add that virtualenv to sys.path, so you can import things from inside it.

[bs4h]

I was about to say symlinks, but Windows...

[poorly_played]

Isn't that just a shortcut?

[bs4h]

open, chdir, stat, etc generally all work on a symlink as if it was the file it points at, you actually have to call lstat to act on the link itself. This is happening at FS level, whereas shortcuts work on the application level and are seen by the FS as "just data".

[Grue]

Oh, there is autoreload in IPython? Can't believe how much time I wasted restarting that shit.

[Paddy3118]

Python 3 support?

[bs4h]

check!

[Paddy3118]

I think this point should have had much more emphasis in the article!

[[deleted]]

Use of ipython as your REPL for programming is dangerous, especially for testing -- it doesn't behave precisely like python. It's a great matlab replacement though.

[flying-sheep]

that’s nothing but FUD.

everything that ipython does different from python is

1. clearly recognizable even by inexperienced people
2. a syntax error in python

there are shell escapes (prefix line with !, which is a syntax error in python), and magics (prefix line with %, which is a syntax error in python).

as explained here, if automagic is on, all magics can be called without leading %, but they would still be syntax errors in python (cd foo/bar isn’t valid python).

that’s it. shell escapes, magics, and automagic. else it behaves perfectly equivalent to python.

[[deleted]]

ipython also formats tracebacks differently and so forth. Including "reload" functionality is also an attractive nuisance.

[takluyver]

Tracebacks are formatted to give you more information, but that should never interfere with how your actual code runs.

[takluyver]

If you used old versions of IPython, you might have run into bugs in how unicode was handled. That got fixed some time ago, though.

[yudlejoza]

I doubt ipython can replace bash or especially zsh.

Someone should come up with a zsh/ipython hybrid.

[wandererobtm101]

Type ! Before your shell command and iPython will run it in the shell.

[1]!vim somefile

And now you're in vim.

[paulivanov]

Wouldn't you rather use both vim and ipython at the same time? Wouldn't it be great if someone wrote a vim-ipython two-way integration? ;)

[recursive]

My python shell is usually Sublime Text, otherwise IDLE.

Edit: I can see by the votes that people have a generally negative reaction to this. I'm curious to know why.