TBVaccine

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TBVaccine is a utility that pretty-prints Python tracebacks. It automatically highlights lines you care about and deemphasizes lines you don't, and colorizes the various elements in a traceback to make it easier to parse.

Here are some screenshots. This is the before:

.. image:: misc/before.png

And this is the after:

.. image:: misc/after.png

If you add the hook or call TBVaccine in your code, it can also print all variables in each stack frame. That is, it turns this:

.. image:: misc/before-vars.png

into this:

.. image:: misc/after-vars.png

Installation

To install, use pip::

pip install tbvaccine

You are done!

Global usage

You can have TBVaccine insert itself all up in your system and stick its tentacles in all your libraries, like a cute, useful Cthulhu. That way, every single Python traceback in your system will be pretty. Just set the TBVACCINE environment variable to 1, and you're done.

E.g. for bash::

export TBVACCINE=1

Or fish::

set -x TBVACCINE=1

If you want to prettify tracebacks even when stderr is not a tty, set TBVACCINE_FORCE to 1::

export TBVACCINE=1
export TBVACCINE_FORCE=1
python -c '1/0' 2>&1 | cat  # pretty!

NOTE: If you're on Ubuntu, you most likely have Apport installed, which overrides TBVaccine's hook with its own. To disable Apport for Python, delete a file named /etc/python<version>/sitecustomize.py. Note that this will disable Apport for Python, and you won't be asked to submit info to Ubuntu when Python programs crash any more. For some, this is a good thing.

Usage as a command-line utility

TBVaccine can be used from the command line several ways.::

python -m tbvaccine myscript.py

Or just pipe STDERR into it from the program you want to watch::

./myscript.py 2>&1 | tbvaccine

And all the tracebacks will now be pretty!

Usage as a Python library

There are various ways to use TBVaccine as a Python library.

Initialize it like so::

from tbvaccine import TBVaccine
tbv = TBVaccine(
    code_dir="/my/code/dir",
    isolate=True
)

code_dir marks the directory we code about. Files under that directory that appear in the traceback will be highlighted. If not passed, the current directory, as returned by os.getcwd() will be used.

If isolate is False, all lines are colorized, and code_dir is ignored.

If show_vars is False, variables will not be printed in each stack frame.

To use it in an except block::

from tbvaccine import TBVaccine
try:
    some_stuff()
except:
    print(TBVaccine().format_exc())

To make it the default way of printing tracebacks, use add_hook() (which also accepts any argument the TBVaccine class does)::

import tbvaccine
tbvaccine.add_hook(isolate=False)

1 / 0

Bam! Instant pretty tracebacks.

Logging integration

You can integrate TBVaccine with logging like so::

class TbVaccineFormatter(logging.Formatter):
    def  formatException(self, exc_info):
        return TBVaccine(isolate=True).format_exc()

sh = logging.StreamHandler()
sh.setFormatter(TbVaccineFormatter('[%(levelname)s] %(asctime)s : %(message)s', '%Y-%m-%d %H:%M:%S'))
logger.addHandler(sh)

Configuration

To configure TBVaccine, open its configuration file in ~/.config/tbvaccine/tbvaccine.cfg (or your operating system's equivalent) and edit it. You can currently configure the color style there by specifying one of the Pygments styles <http://pygments.org/demo/6778888/?style=monokai>.

Epilogue

This library is still pretty new, please contribute patches if something doesn't work as intended, and also please tell your friends about it! Hopefully one day it will be implemented in the Python interpreters themselves.

-- Stavros