pdb++, a drop-in replacement for pdb
.. -- restructuredtext --
This module is an extension of the pdb_ module of the standard library. It is meant to be fully compatible with its predecessor, yet it introduces a number of new features to make your debugging experience as nice as possible.
.. image:: https://github.com/antocuni/pdb/blob/master/screenshot.png?raw=true
pdb++ features include:
colorful TAB completion of Python expressions (through fancycompleter_)
optional syntax highlighting of code listings (through pygments_)
sticky mode_
several new commands to be used from the interactive (Pdb++) prompt
smart command parsing_ (hint: have you ever typed r or c at the
prompt to print the value of some variable?)
additional convenience functions in the pdb module, to be used from
your program
pdb++ is meant to be a drop-in replacement for pdb. If you find some
unexpected behavior, please report it as a bug.
.. _pdb: http://docs.python.org/library/pdb.html .. _fancycompleter: http://bitbucket.org/antocuni/fancycompleter .. _pygments: http://pygments.org/
Since pdb++ is not a valid identifier for pip and easy_install,
the package is named pdbpp::
$ pip install pdbpp
-- OR --
$ easy_install pdbpp
pdb++ is also available via conda_::
$ conda install -c conda-forge pdbpp
Alternatively, you can just put pdb.py somewhere inside your
PYTHONPATH.
.. _conda: https://anaconda.org/conda-forge/pdbpp
Note that the module is called pdb.py so that pdb++ will automatically
be used in all places that do import pdb (e.g. pytest --pdb will
give you a pdb++ prompt).
The old pdb module is still available by doing e.g. import pdb; pdb.pdb.set_trace().
The following are new commands that you can use from the interative
(Pdb++) prompt.
.. _sticky mode:
sticky [start end]
Toggle sticky mode. When in this mode, every time the current position
changes, the screen is repainted and the whole function shown. Thus, when
doing step-by-step execution you can easily follow the flow of the
execution. If start and end are given, sticky mode is enabled and
only lines within that range (extremes included) will be displayed.
longlist (ll)
List source code for the current function. Different from the normal pdb
list command, longlist displays the whole function. The current
line is marked with ->. In case of post-mortem debugging, the line
which actually raised the exception is marked with >>. If the
highlight config option_ is set and pygments_ is installed, the source
code is highlighted.
interact
Start an interative interpreter whose global namespace contains all the
names found in the current scope.
track EXPRESSION
Display a graph showing which objects are the value of the expression refers
to and are referred by. This command requires the pypy source code to
be importable.
display EXPRESSION
Add an expression to the display list; expressions in this list are
evaluated at each step, and printed every time its value changes.
WARNING: since these expressions are evaluated multiple times, make sure
not to put expressions with side-effects in the display list.
undisplay EXPRESSION:
Remove EXPRESSION from the display list.
source EXPRESSION
Show the source code for the given function/method/class.
edit EXPRESSION
Open the editor in the right position to edit the given
function/method/class. The editor used is specified in a config option_.
hf_unhide, hf_hide, hf_list
Some frames might be marked as "hidden" by e.g. using the @pdb.hideframe_
function decorator. By default, hidden frames are not shown in the stack
trace, and cannot be reached using up and down. You can use
hf_unhide to tell pdb to ignore the hidden status (i.e., to treat hidden
frames as normal ones), and hf_hide to hide them again. hf_list
prints a list of hidden frames.
The config option enable_hidden_frames can be used to disable handling
of hidden frames in general.
By default, pdb tries hard to interpret what you enter at the command prompt as one of its builtin commands. However, this is inconvenient if you want to just print the value of a local variable which happens to have the same name as one of the commands. E.g.::
(Pdb) list
1
2 def fn():
3 c = 42
4 import pdb;pdb.set_trace()
5 -> return c
(Pdb) c
In the example above, instead of printing 42 pdb interprets the input as the
command continue, and then you loose your prompt. It's even worse than
that, because it happens even if you type e.g. c.__class__.
pdb++ fixes this unfriendly (from the author's point of view, of course :-))
behavior by always prefering variable in scope, if it exists. If you really
want to execute the corresponding command, you can prefix it with !!.
Thus, the example above becomes::
(Pdb++) list
1
2 def fn():
3 c = 42
4 import pdb;pdb.set_trace()
5 -> return c
(Pdb++) c
42
(Pdb++) !!c
Note that the "smart" behavior takes place only when there is ambiguity, i.e. if there exists a variable with the same name as a command: in all other cases, everything works as usual.
Regarding the list command itself, using list(… is a special case
that gets handled as the Python builtin::
(Pdb++) list([1, 2])
[1, 2]
pdb moduleThe pdb module that comes with pdb++ includes all the functions and
classes that are in the module from the standard library. If you find any
difference, please report it as a bug.
In addition, there are some new convenience functions that are unique to pdb++.
pdb.xpm()
eXtended Post Mortem: it is equivalent to
pdb.post_mortem(sys.exc_info()[2]). If used inside an except
clause, it will start a post-mortem pdb prompt from the line that raised the
exception being caught.
pdb.disable()
Disable pdb.set_trace(): any subsequent call to it will be ignored.
pdb.enable()
Re-enable pdb.set_trace(), in case it was disabled by pdb.disable().
.. _@pdb.hideframe:
@pdb.hideframe
A function decorator that tells pdb++ to hide the frame corresponding to the
function. Hidden frames do not show up when using interactive commands such
as up, down or where, unless hf_unhide is invoked.
@pdb.break_on_setattr(attrname, condition=always)
class decorator: break the execution of the program every time the
attribute attrname is set on any instance of the class. condition is
a callable that takes the target object of the setattr and the actual value;
by default, it breaks every time the attribute is set. E.g.::
@break_on_setattr('bar')
class Foo(object):
pass
f = Foo()
f.bar = 42 # the program breaks here
If can be used even after the class has already been created, e.g. if we want to break when some attribute of a particular object is set::
class Foo(object):
pass
a = Foo()
b = Foo()
def break_if_a(obj, value):
return obj is a
break_on_setattr('bar', condition=break_if_a)(Foo)
b.bar = 10 # no break
a.bar = 42 # the program breaks here
This can be used after pdb.set_trace() also::
(Pdb++) import pdb
(Pdb++) pdb.break_on_setattr('tree_id')(obj.__class__)
(Pdb++) continue
.. _config option:
To customize pdb++, you can put a file named .pdbrc.py in your home
directory. The file must contain a class named Config inheriting from
pdb.DefaultConfig and override the desired values.
The following is a list of the options you can customize, together with their default value:
prompt = '(Pdb++) '
The prompt to show when in interactive mode.
highlight = True
Highlight line numbers and the current line when showing the longlist of
a function or when in sticky mode.
encoding = 'utf-8'
File encoding. Useful when there are international characters in your string
literals or comments.
sticky_by_default = False
Determine whether pdb++ starts in sticky mode or not.
line_number_color = Color.turquoise
The color to use for line numbers.
filename_color = Color.yellow
The color to use for file names when printing the stack entries.
current_line_color = "39;49;7"
The SGR parameters for the ANSI escape sequence to highlight the current
line.
This is set inside the SGR escape sequence \e[%sm where \e is the
ESC character and %s the given value. See SGR parameters_.
The following means "reset all colors" (0), set foreground color to 18
(48;5;18), and background to 21.
The default uses the default foreground (39) and background (49)
colors, inversed (7).
use_pygments = True
If pygments_ is installed and highlight == True, apply syntax highlight
to the source code when showing the longlist of a function or when in
sticky mode.
bg = 'dark'
Passed directly to the pygments.formatters.TerminalFormatter constructor.
Selects the color scheme to use, depending on the background color of your
terminal. If you have a light background color, try to set it to
'light'.
colorscheme = None
Passed directly to the pygments.formatters.TerminalFormatter constructor.
It expects a dictionary that maps token types to (lightbg, darkbg) color names or
None (default: None = use builtin colorscheme).
editor = '${EDITOR:-vi}'
The command to invoke when using the edit command. By default, it uses
$EDITOR if set, else vi. The command must support the standard
notation COMMAND +n filename to open filename at line n. emacs
and vi are known to support this.
truncate_long_lines = True
Truncate lines which exceed the terminal width.
exec_if_unfocused = None
Shell command to execute when starting the pdb prompt and the terminal
window is not focused. Useful to e.g. play a sound to alert the user that
the execution of the program stopped. It requires the wmctrl_ module.
disable_pytest_capturing = False
Old versions of pytest_ crash when you execute pdb.set_trace() in a
test, but the standard output is captured (i.e., without the -s option,
which is the default behavior). When this option is on, the stdout
capturing is automatically disabled before showing the interactive prompt.
enable_hidden_frames = True
Certain frames can be hidden by default.
If enabled, the commands hf_unhide, hf_hide, and hf_list can be
used to control display of them.
show_hidden_frames_count = True
If enable_hidden_frames is True this controls if the number of
hidden frames gets displayed.
def setup(self, pdb): pass
This method is called during the initialization of the Pdb class. Useful
to do complex setup.
show_traceback_on_error = True
Display tracebacks for errors via Pdb.error, that come from
Pdb.default (i.e. the execution of an unrecognized pdb command),
and are not a direct cause of the expression itself (e.g. NameError
with a command like doesnotexist).
With this option disabled only *** exception string gets printed, which
often misses useful context.
show_traceback_on_error_limit = None
This option sets the limit to be used with traceback.format_exception,
when show_traceback_on_error is enabled.
.. _wmctrl: http://bitbucket.org/antocuni/wmctrl
.. _pytest: https://pytest.org/
.. _SGR parameters: https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters
pdb++ is developed using Test Driven Development, and we try to keep test
coverage high.
As a general rule, every commit should come with its own test. If it's a new feature, it should come with one or many tests which excercise it. If it's a bug fix, the test should fail before the fix, and pass after.
The goal is to make refactoring easier in the future: if you wonder why a certain line of code does something, in principle it should be possible to comment it out and see which tests fail.
In exceptional cases, the test might be too hard or impossible to write: in that cases it is fine to do a commmit without a test, but you should explain very precisely in the commit message why it is hard to write a test and how to reproduce the buggy behaviour by hand.
It is fine NOT to write a test in the following cases:
typos, documentation, and in general any non-coding commit
code refactorings which do not add any feature
commits which fix an already failing test
commits to silence warnings
purely cosmetic changes, such as change the color of the output
Minor bugfix release, moving Continuous Integration from Travis/AppVeyor to GitHub Actions, based on changes on master, but without the (more invasive) (test) fixes for Windows.
Fixes
Misc
Minor bugfix release to make pdb++ work better with a system-wide installation from within a virtualenv.
Fixes
Version 0.10.2 fixes only the deployment configuration.
Changes
config: improve current_line_color: default fg/bg/inversed (#188)
Show tracebacks for errors with interactively run code (#185)
This adds new config settings "show_traceback_on_error" (default: True), and "show_traceback_on_error_limit" (default: None).
Fixes
Fix get_stack for non-last index (#192)
This fixes a pretty nasty bug, which was triggered e.g. with the "next" command running into a deeper exception, and the internal stack getting confused (if hidden frames are involved).
Misc:
Fixes
Misc
Fixes
Features
skip=["importlib._bootstrap_external"].Misc
Fixes
Features
Misc
Fixes
Misc
Fixes
NOTE: 0.9.9 and 0.9.10 were not released to PyPI due to Travis CI misconfiguration.
Fixes
Misc
Fixes
Fixes
Fixes
python -m pdb … (#135)Misc
shutil.get_terminal_size if available (#125)NOTE: 0.9.4 was not released to PyPI due to Travis CI misconfiguration.
Features
Fixes
pdb.set_trace() (#119)Tests
--assert=plain modeMisc
LICENSE.txt.__version__.Install ordereddict package only on Python versions older than 2.7.
Python 3 support
Improved Windows support
backports.inspectfuncsigs optional.Python 3 compatibility
Optional support for 256 color formatting by setting
use_terminal256formatter = True in ~/.pdbrc.py
(https://bitbucket.org/antocuni/pdb/pull-request/30)
Make set_trace() in same program remember previous state
(https://bitbucket.org/antocuni/pdb/pull-request/33)
Append ? and ?? to callable to get info a la IPython
(https://bitbucket.org/antocuni/pdb/pull-request/25)
Don't treat lines like r = 5 or c = 6 as commands
(https://bitbucket.org/antocuni/pdb/pull-request/11)
fix issue 20: support argument-free post mortem
py.testThe pp (pretty print) command now uses the actual width of the terminal,
instead of hardcoding 80 columns
py.test and unittest internal frames are hidden by default (type help hidden_frames for more info)
don't crash if py is installed but py.test is not