Error handling behaving differently for rule syntax and python code about clipspy HOT 3 CLOSED

CLIPS does not implement exceptions. Therefore, it won't raise any CLIPSError when invoking the run function. The run function always returns the amount of fired rules.

The reason why you see a CLIPSError when you add a typo in your code is because the build function fails to build the code due to your typo.

What is happening is your function throws the error and stops the execution of your CLIPS rules. This mechanism is silent and the only way for you to verify whether everything ran smoothly is via the CLIPS get-error function.

env = clips.Environment()

try:
    env.define_function(is_date_in_range)
    env.build(rule)

    env.assert_string("(issue_date \"gibberish\")")
    env.run()
    print(env.eval('(get-error)'))
except Exception as error:
    print("Found an error")

Will print:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/dist-packages/clips/functions.py", line 440, in python_function
    ret = environment_data(env, 'user_functions')[funcname](*arguments)
  File "/home/noxdafox/issue-48.py", line 6, in is_date_in_range
    date = datetime.strptime(date, "%Y-%m-%d")
  File "/usr/lib/python3.9/_strptime.py", line 568, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
  File "/usr/lib/python3.9/_strptime.py", line 349, in _strptime
    raise ValueError("time data %r does not match format %r" %
ValueError: time data 'gibberish' does not match format '%Y-%m-%d'

Nevertheless, the mechanism is indeed imperfect and the library should be more explicit when handling these situations. I will soon come with improvements in merit.

from clipspy.

Awesome! Thanks for the answer, that will already help me proceed with my developments!

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Issue fixed in release 1.0.1.

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