PYTHONOPTIMIZE in an IPython/Jupyter Notebook

Question

How do I disable assertions and docstrings, respectively, in an IPython session or a Jupyter Notebook?

After the official python documentation, this stackoverflow question and this answer to a similar question, I may “set the PYTHONOPTIMIZE environment variable to 1”. Well, if I set the environment variable following this blog post via

%env PYTHONOPTIMIZE=1

I can successfully list the value along all other variables with %env, but still unexpectedly __debug__ == True and AssertionErrors are raised. Different values like 2 or a string "1" weren't successful, either.

Bonus question: Is it possible to disable assert only for a specific (local) library, like after using import myfancylib, myfancylib.eggs() won't raise?

Serge3leo · Accepted Answer · 2023-02-02 14:11:46Z

0

I am not aware of a way to disable assert only for the currently active session. However, there are a couple of other options.

Non volatile disable assert for current conda environment:

_disable_assert = True
_disable_assert_msg = "To make your changes take effect please Save and restart Jupyter Notebook\n"
if _disable_assert:
    try:
        assert False
        print("OK - assert disabled")
    except AssertionError:
        import os
        import sys
        
        os.system("conda env config vars set PYTHONOPTIMIZE=1")
        print(_disable_assert_msg, file=sys.stderr)
        assert False, _disable_assert_msg
else:
    try:
        assert False

        import os
        import sys

        os.system("conda env config vars unset PYTHONOPTIMIZE")
        print(_disable_assert_msg, file=sys.stderr)
        _zero_division = 1/0
    except AssertionError:
        print("OK - assert enabled")

Disable assert for cell:

%%python -O 
# Only for one cell. This cell is run in a separate process.

import sys
import os

print(__debug__)
print(sys.argv)
print(os.environ)

try:
    assert False
    print("Assert disable")
except AssertionError:
    print("Assert enable")

edited Feb 2, 2023 at 14:11

answered Feb 2, 2023 at 12:30

Serge3leo

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4 Comments

aaron Over a year ago

You mean just setting a global variable _disable_assert = True works?

Serge3leo Over a year ago

@aaron, Sorry, I didn't understand your question. _disable_assert and _disable_assert_msg are internal variables of this code snippet. They start with _ to reduce the likelihood of conflict with other parts of the code.

Serge3leo Over a year ago

@aaron, There are several ways to set the PYTHONOPTIMIZE variable before starting python: command-line utilities, editing configuration files, etc. Personally, I find this method of change convenient, directly in notepad. It seems that the author of the question was also looking for something similar to %env.

aaron Over a year ago

Ah, it would be clearer to define that in a function def set_disable_alert(disable_assert):. Your code snippet as-is appears to imply that setting the global variable _disable_assert = True disables assert.

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