Replace sys.exit() with specific error about dendrify HOT 3 CLOSED

Implemented in the development branch, will be pushed to main soon. Thanks

from dendrify.

sys.exit() raises a SystemExit error (not a SystemError). So I don't think that calling sys.exit() is misleading. One advantage of exiting in this way is that you avoid getting very long error messages that include traceback calls (see https://softhints.com/how-to-print-error-message-traceback-python/). However, I do agree that my previous implementation has some room for improvements (e.g. remove prints). Thank you for your suggestion.

from dendrify.

As far as simply exiting the program is concerned, SystemExit is not misleading. As far as user-friendliness and usability are concerned, it is. Because it is too generic, abrupt for the user and unhelpful for a developer. In the places where you use it, the errors are very specific. SystemExit is not as informative and it is normally used for scripts (not importable modules). Also, SystemExit is a special type of exception that won't be caught by a try: ... except Exception: .... Specific errors help other developers that might build on top of yours catch them, if something goes wrong, and handle them however they want. Since this a library intended to be used elsewhere and not just a little script, sys.exit() is bad practice here.

Just raise a specific exception. That will both:

• cause the process to exit, as you intend
• notify the user with an informative backtrace (e.g. value error occured here, with a specific message)

It's up to the user of your library as to how to handle "very long error messages". E.g. if I wanna use dendrify in a script, I can just catch your specific error, and print my own message.

See:

• https://www.reddit.com/r/Python/comments/7xdi5r/is_sysexit_bad_practice/ (discussion on this topic)
• ScilifelabDataCentre/dds_cli#78 (comment) ("Doing a hard system exit is an absolute last resort.")
• https://mail.python.org/pipermail/python-list/2016-April/857869.html ("...How rude! Instead, let the
  exception bubble out...")

from dendrify.