Vpack

A package containing a lot of useful utilities for Python developing and debugging.

Features

• Sigview: press Ctrl+C to print the current stack instead of exiting.
• Breakpt: set always-on, at-time, on-error breakpoints conveniently.
• Reload: reload modules by names.

To-do:

• Vartrace: figure out how a variable changes over time, with a statistical chart or a live counter.

Installation

pip install --upgrade vpack

Examples

Sigview

Sigview is a signal handler. It will print the current running information (e.g. file, lineno, code, stack) when Ctrl+C is pressed.

Enable sigview:

from vpack import sigview
sigview.enable()
# your code goes here

Now run your script and you will see the following output:

$ python examples/sigview_example.py
(vpack): Sigview enabled. Press ^C to see the current frame. Press ^C again to exit.
1
2
1

Press Ctrl+C to see the current frame, possible outputs:

^C(vpack): Current file:
examples/sigview_example.py:11 in main
(vpack): Current stask:
+----------------------------------------------------------+
| File "examples/sigview_example.py", line 14, in <module> |
|   main()                                                 |
|                                                          |
| File "examples/sigview_example.py", line 11, in main     |
|   time.sleep(2)                                          |
+----------------------------------------------------------+

Press Ctrl+C twice (in 0.5 seconds) to exit.

You can also use sigview.enable(openshell=True) to open a new shell when Ctrl+C is pressed.

See sigview_example.py and sigview_openshell_example.py.md for more details.

Breakpt

Breakpt is a convenient way to set breakpoints.

.at(n) will try to open an interactive IPython shell (or pdb) when this line has been executed n times. .onerror() will try to open a PDB shell when an Exception is raised.

You can use breakpt.enable() and breakpt.disable() to enable and disable breakpt.

from vpack import breakpt

for i in range(10):
    print(i)
    breakpt.at(8) # break at i = 7
    breakpt.at(5) # break at i = 4

for i in range(6):
    print(i)
    if i == 2: breakpt.disable() # disable breakpt
    if i == 4: breakpt.enable() # enable breakpt
    breakpt.always() # break at i = 0, 1, 4, 5

breakpt.onerror()
a = [1, 2, 3]
for i in range(5):
    print(a[i]) # will break at i = 3

See breakpt_example.py for more details.

Reload

Reload modules by names, see reload_example.py for more details.