pyterminate 0.0.2

Exit programs gracefully.

pyterminate

Reliably run cleanup code upon program termination.

Table of Contents

• Why does this exist?
• What can it do?
• Quickstart

Why does this exist?

There are currently two builtin modules for handling termination behavior in Python: atexit and signal. However, using them directly leads to a lot of repeated boilerplate code, and some non-obvious behaviors that can be easy to accidentally get wrong, which is why I wrote this package.

The atexit module is currently insufficient since it fails to handle signals. The signal module is currently insufficient since it fails to handle normal or exception-caused exits.

Typical approaches would include frequently repeated code registering a function both with atexit and on desired signals. However, extra care sometimes needs to be taken to ensure the function doesn't run twice (or is idempotent), and that a previously registered signal handler gets called.

What can it do?

This packages does or allows the following behavior:

• Register a function to be called on program termination

  • Always on normal or exception-caused termination: @pyterminate.register
  • Configurable for any desired signals:
    @pyterminate.register(signals=(signal.SIGINT, signal.SIGABRT))

• Allows multiple functions to be registered

• Will call previous registered signal handlers

• Allows zero or non-zero exit codes on captured signals:
  @pyterminate.register(successful_exit=True)

• Allows suppressing or throwing of KeyboardInterrupt on SIGINT:
  @pyterminate.register(keyboard_interrupt_on_sigint=True)

  • You may want to throw a KeyboardInterrupt if there is additional exception handling defined.

• Allows functions to be unregistered: pyterminate.unregister(func)

• Ignore multiple repeated signals to allow the registered functions to complete

  • However, it can be canceled upon receipt of another signal. Desired behavior could vary application to application, but this feels appropriate for the most common known use cases.

Quickstart

python3 -m pip install pyterminate

import signal

import pyterminate

@pyterminate.register(
    args=(None,),
    kwargs={"b": 42},
    signals=(signal.SIGINT, signal.SIGTERM),
    successful_exit=True,
    keyboard_interrupt_on_sigint=True
)
def cleanup(*args, **kwargs):
    ...

# or

pyterminate.register(cleanup, ...)