Pretty Traceback

Human readable stacktraces for Python.

Project/Repo:

Code Quality/CI:

Overview

Pretty Traceback groups together what belongs together, adds coloring and alignment. All of this makes it easier for you to see patterns and filter out the signal from the noise. This tabular format is best viewed in a wide terminal.

In other words, get this 😍

Instead of this 🤮

Traceback (most recent call last):
  File "/home/user/venvs/py38/bin/myproject", line 12, in <module>
    sys.exit(cli())
  File "/home/user/venvs/py38/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/user/venvs/py38/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/user/venvs/py38/lib/python3.8/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/user/venvs/py38/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/user/venvs/py38/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/user/foss/myproject/src/myproject/cli.py", line 148, in build
    lp_gen_docs.gen_html(built_ctx, html_dir)
  File "/home/user/foss/myproject/src/myproject/gen_docs.py", line 295, in gen_html
    wrapped_html = wrap_content_html(content_html, 'screen', meta, toc)
  File "/home/user/foss/myproject/src/myproject/gen_docs.py", line 238, in wrap_content_html
    result = tmpl.render(**ctx)
  File "/home/user/venvs/py38/lib/python3.8/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/home/user/venvs/py38/lib/python3.8/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/home/user/venvs/py38/lib/python3.8/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "<template>", line 56, in top-level template code
TypeError: no loader for this environment specified

If you're terminal is not wide enough, the long paths are replaced with aliases.

Usage

Add the following to your __main__.py or the equivalent module which is your entry point.

try:
    import pretty_traceback
    pretty_traceback.install()
except ImportError:
    pass    # no need to fail because of missing dev dependency

Please do not add this code e.g. to your __init__.py or any other module that your users may import. They may not want you to mess with how their tracebacks are printed.

If you do feel the overwhelming desire to import the pretty_traceback in code that others might import, consider using the envvar argument, which will cause the install function to effectively be a noop unless you set ENABLE_PRETTY_TRACEBACK=1.

try:
    import pretty_traceback
    pretty_traceback.install(envvar='ENABLE_PRETTY_TRACEBACK')
except ImportError:
    pass    # no need to fail because of missing dev dependency

Note, that the hook is only installed if the existing hook is the default. Any existing hooks that were installed before the call of pretty_traceback.install will be left in place.

LoggingFormatter

A logging.Formatter subclass is also available (e.g. for integration with flask).

import os
from flask.logging import default_handler

try:
    if os.getenv('FLASK_DEBUG') == "1":
        import pretty_traceback
        default_handler.setFormatter(pretty_traceback.LoggingFormatter())
except ImportError:
    pass    # no need to fail because of missing dev dependency

More Examples

Alternatives

Pretty Traceback is heavily inspired by the backtrace module by nir0s.

• https://github.com/nir0s/backtrace
• https://github.com/willmcgugan/rich#tracebacks
• https://github.com/aroberge/friendly-traceback
• https://github.com/laurb9/rich-traceback
• https://github.com/staticshock/colored-traceback.py
• https://github.com/chillaranand/ptb

Changelog for https://github.com/mbarkhau/pretty-traceback

2020.1010

• Fix #5: Only show aliases that were actually used.
• Fix #5: Better alignment on narrow terminals.

2020.1009

• Fix #3: Corner case where exception has None as context.
• Fix #2: Improve formatting when line overflows.

2020.1008

• Add pretty_traceback.LoggingFormatter

2020.1006

• Add wide mode.

2020.1005

• Update formatting to work better with recursive calls.
• Add tests

2020.1001

• Initial release