Is it possible to go into ipython from code?

Question

For my debugging needs, pdb is pretty good. However, it would be much cooler (and helpful) if I could go into ipython. Is this thing possible?

Solution 1

There is an ipdb project which embeds iPython into the standard pdb, so you can just do:

import ipdb; ipdb.set_trace()

It's installable via the usual pip install ipdb.

ipdb is pretty short, so instead of easy_installing you can also create a file ipdb.py somewhere on your Python path and paste the following into the file:

import sys
from IPython.Debugger import Pdb
from IPython.Shell import IPShell
from IPython import ipapi

shell = IPShell(argv=[''])

def set_trace():
    ip = ipapi.get()
    def_colors = ip.options.colors
    Pdb(def_colors).set_trace(sys._getframe().f_back)

Solution 2

In IPython 0.11, you can embed IPython directly in your code like this

Your program might look like this

In [5]: cat > tmpf.py
a = 1

from IPython import embed
embed() # drop into an IPython session.
        # Any variables you define or modify here
        # will not affect program execution

c = 2

^D

This is what happens when you run it (I arbitrarily chose to run it inside an existing ipython session. Nesting ipython sessions like this in my experience can cause it to crash).

In [6]:

In [6]: run tmpf.py
Python 2.7.2 (default, Aug 25 2011, 00:06:33)
Type "copyright", "credits" or "license" for more information.

IPython 0.11 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: who
a       embed

In [2]: a
Out[2]: 1

In [3]:
Do you really want to exit ([y]/n)? y


In [7]: who
a       c       embed

Solution 3

If you're using a more modern version of IPython (> 0.10.2) you can use something like

from IPython.core.debugger import Pdb
Pdb().set_trace()

But it's probably better to just use ipdb

Solution 4

The equivalent of

import pdb; pdb.set_trace()

with IPython is something like:

from IPython.ipapi import make_session; make_session()
from IPython.Debugger import Pdb; Pdb().set_trace()

It's a bit verbose, but good to know if you don't have ipdb installed. The make_session call is required once to set up the color scheme, etc, and set_trace calls can be placed anywhere you need to break.

Solution 5

I like to simply paste this one-liner in my scripts where I want to set a breakpoint:

__import__('IPython').Debugger.Pdb(color_scheme='Linux').set_trace()

Newer version might use:

__import__('IPython').core.debugger.Pdb(color_scheme='Linux').set_trace()

View more solutions

Comments

[MarkD]

so there's no way of writing something like ipython.set_trace() ? :)

[Xiong Chiamiov]

Works amazingly well with Django. Well, except the fact that I can't see the text I'm typing, but that's probably easily fixible (since ipdb's only six lines).

[Jeremy Dunck]

Actually, the issue there is that Django forks a separate thread for the runserver, and any time you make a code edit, it respawns the thread. This normally works fine, but if you're sitting in pdb when the thread gets killed, the terminal goes insane. You can fix this by breaking out of runserver, runniny 'stty sane', then starting runserver again.

[joon]

This dropping into an IPython session is very cool. Thank you so much!

[gerrit]

I foolishly placed this inside an (almost infinite) loop. How can I ever get out?

[confused00]

@gerrit, press Ctrl + d if you are still in there.

[gerrit]

@confused00 That would have been mightily infinite, 6 months later ;-)

[ostrokach]

ImportError: No module named 'IPython.Debugger' on python 3.4 / IPython 3

[alisianoi]

Thank you! A bit simpler: ipython --pdb -- ./path/to/my/script --with-args here

[Xiong Chiamiov]

One advantage this has over pdb and ipdb is that any exceptions caused by the code you run get full tracebacks (because you aren't already "in" one). This is super useful for me, since I have a tendency to use pdb as a way to set up a bunch of variables for an interactive shell.

[SebMa]

@daniel-roseman Hi, I get ModuleNotFoundError: No module named 'IPython.Debugger', ModuleNotFoundError: No module named 'IPython.Shell' and ImportError: cannot import name 'ipapi'

[SebMa]

@memoselyk Hi, I get ModuleNotFoundError: No module named 'IPython.Debugger', ModuleNotFoundError: No module named 'IPython.Shell' and ImportError: cannot import name 'ipapi'

[Jim K.]

This is the right answer folks. ipdb is great, but it's not even close to the same UX as ipython.

[MatrixManAtYrService]

@gerrit, If you're stuck in an embed loop: def f() : pass ; IPython.embed = f so that the embed() call is a noop, then Ctrl + D

[gerrit]

There is a way to get the breakpoint() function to get into ipdb.