Exception Printing

The e mark decides what happens when an exception object is among the arguments.

:e0 — plain

No special handling; the exception is printed like any other value.

import neoprint as np

try:
    1 / 0
except ZeroDivisionError as e:
    np.show(e, ':e0')

main.py:6   | division by zero

:e1 — red message

The message is printed in red, without a traceback:

np.show(e, ':e1')

Use it when you only want to signal a failure, not explain it.

:e2 — traceback panel (default)

This is what bare :e does. The exception is rendered through Rich’s traceback renderer:

np.show(e, ':e2')

The panel includes the source snippet of every frame, with the failing line marked.

:e3 — traceback with locals

Same as :e2, plus the local variables of each frame:

np.show(e, ':e3')

Useful when the bug depends on values you cannot guess from the code. Locals whose names start with dunder or sunder (__x__, _x_) are hidden.

Printing the current exception

Inside an except block you can omit the argument entirely; neoprint reads the current exception from sys.exc_info():

try:
    load_config()
except Exception:
    np.show(':e')       # same as np.show(':e2')

Combining with other marks

e combines freely with v, d, and i:

np.show(e, ':v8')       # one red line, no traceback

Shorthand

from neoprint import exception

try:
    ...
except Exception as e:
    exception(e)        # same as np.show(e, ':e2')

Global excepthook

When config.rich_traceback is on (the default), uncaught exceptions are printed by Rich’s excepthook instead of Python’s bare traceback, without any call to np.show. Set show_traceback_locals to include locals there too:

import neoprint as np

np.config(show_traceback_locals=True)

See Configuration.