ultraTB

Module: ultraTB

Inheritance diagram for IPython.ultraTB:

ultraTB.py – Spice up your tracebacks!

• ColorTB

I’ve always found it a bit hard to visually parse tracebacks in Python. The ColorTB class is a solution to that problem. It colors the different parts of a traceback in a manner similar to what you would expect from a syntax-highlighting text editor.

Installation instructions for ColorTB:

import sys,ultraTB sys.excepthook = ultraTB.ColorTB()

• VerboseTB

I’ve also included a port of Ka-Ping Yee’s “cgitb.py” that produces all kinds of useful info when a traceback occurs. Ping originally had it spit out HTML and intended it for CGI programmers, but why should they have all the fun? I altered it to spit out colored text to the terminal. It’s a bit overwhelming, but kind of neat, and maybe useful for long-running programs that you believe are bug-free. If a crash does occur in that type of program you want details. Give it a shot–you’ll love it or you’ll hate it.

Note:

The Verbose mode prints the variables currently visible where the exception happened (shortening their strings if too long). This can potentially be very slow, if you happen to have a huge data structure whose string representation is complex to compute. Your computer may appear to freeze for a while with cpu usage at 100%. If this occurs, you can cancel the traceback with Ctrl-C (maybe hitting it more than once).

If you encounter this kind of situation often, you may want to use the Verbose_novars mode instead of the regular Verbose, which avoids formatting variables (but otherwise includes the information and context given by Verbose).

Installation instructions for ColorTB:

import sys,ultraTB sys.excepthook = ultraTB.VerboseTB()

Note: Much of the code in this module was lifted verbatim from the standard library module ‘traceback.py’ and Ka-Ping Yee’s ‘cgitb.py’.

• Color schemes

The colors are defined in the class TBTools through the use of the ColorSchemeTable class. Currently the following exist:

• NoColor: allows all of this module to be used in any terminal (the color

escapes are just dummy blank strings).

• Linux: is meant to look good in a terminal like the Linux console (black

or very dark background).

• LightBG: similar to Linux but swaps dark/light colors to be more readable

in light background terminals.

You can implement other color schemes easily, the syntax is fairly self-explanatory. Please send back new schemes you develop to the author for possible inclusion in future releases.

Classes

AutoFormattedTB

class IPython.ultraTB.AutoFormattedTB(mode='Plain', color_scheme='Linux', tb_offset=0, long_header=0, call_pdb=0, include_vars=0)

Bases: IPython.ultraTB.FormattedTB

A traceback printer which can be called on the fly.

It will find out about exceptions by itself.

A brief example:

AutoTB = AutoFormattedTB(mode = ‘Verbose’,color_scheme=’Linux’) try:

...

except:

AutoTB() # or AutoTB(out=logfile) where logfile is an open file object

__init__()

text()

ColorTB

class IPython.ultraTB.ColorTB(color_scheme='Linux', call_pdb=0)

Bases: IPython.ultraTB.FormattedTB

Shorthand to initialize a FormattedTB in Linux colors mode.

__init__()

FormattedTB

class IPython.ultraTB.FormattedTB(mode='Plain', color_scheme='Linux', tb_offset=0, long_header=0, call_pdb=0, include_vars=0)

Bases: IPython.ultraTB.VerboseTB, IPython.ultraTB.ListTB

Subclass ListTB but allow calling with a traceback.

It can thus be used as a sys.excepthook for Python > 2.1.

Also adds ‘Context’ and ‘Verbose’ modes, not available in ListTB.

Allows a tb_offset to be specified. This is useful for situations where one needs to remove a number of topmost frames from the traceback (such as occurs with python programs that themselves execute other python code, like Python shells).

__init__()

context()

plain()

set_mode()

Switch to the desired mode.

If mode is not specified, cycles through the available modes.

text()

Return formatted traceback.

If the optional mode parameter is given, it overrides the current mode.

verbose()

ListTB

class IPython.ultraTB.ListTB(color_scheme='NoColor')

Bases: IPython.ultraTB.TBTools

Print traceback information from a traceback list, with optional color.

Calling: requires 3 arguments:

(etype, evalue, elist)

as would be obtained by:

etype, evalue, tb = sys.exc_info() if tb:

elist = traceback.extract_tb(tb)

else:

elist = None

It can thus be used by programs which need to process the traceback before printing (such as console replacements based on the code module from the standard library).

Because they are meant to be called without a full traceback (only a list), instances of this class can’t call the interactive pdb debugger.

__init__()

text()

Return a color formatted string with the traceback info.

TBTools

class IPython.ultraTB.TBTools(color_scheme='NoColor', call_pdb=False)

Basic tools used by all traceback printer classes.

__init__()

color_toggle()

Toggle between the currently active color scheme and NoColor.

set_colors()

Shorthand access to the color table scheme selector method.

VerboseTB

class IPython.ultraTB.VerboseTB(color_scheme='Linux', tb_offset=0, long_header=0, call_pdb=0, include_vars=1)

Bases: IPython.ultraTB.TBTools

A port of Ka-Ping Yee’s cgitb.py module that outputs color text instead of HTML. Requires inspect and pydoc. Crazy, man.

Modified version which optionally strips the topmost entries from the traceback, to be used with alternate interpreters (because their own code would appear in the traceback).

__init__()

Specify traceback offset, headers and color scheme.

Define how many frames to drop from the tracebacks. Calling it with tb_offset=1 allows use of this handler in interpreters which will have their own code at the top of the traceback (VerboseTB will first remove that frame before printing the traceback info).

debugger()

Call up the pdb debugger if desired, always clean up the tb reference.

Keywords:

• force(False): by default, this routine checks the instance call_pdb

flag and does not actually invoke the debugger if the flag is false. The ‘force’ option forces the debugger to activate even if the flag is false.

If the call_pdb flag is set, the pdb interactive debugger is invoked. In all cases, the self.tb reference to the current traceback is deleted to prevent lingering references which hamper memory management.

Note that each call to pdb() does an ‘import readline’, so if your app requires a special setup for the readline completers, you’ll have to fix that by hand after invoking the exception handler.

handler()

text()

Return a nice text document describing the traceback.

Functions

IPython.ultraTB.findsource()

Return the entire source file and starting line number for an object.

The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a list of all the lines in the file and the line number indexes a line in that list. An IOError is raised if the source code cannot be retrieved.

FIXED version with which we monkeypatch the stdlib to work around a bug.

IPython.ultraTB.fix_frame_records_filenames()

Try to fix the filenames in each record from inspect.getinnerframes().

Particularly, modules loaded from within zip files have useless filenames attached to their code object, and inspect.getinnerframes() just uses it.

IPython.ultraTB.inspect_error()

Print a message about internal inspect errors.

These are unfortunately quite common.