What are the implications of running python with the optimize flag?

Question

I cannot seem to find a good simple explanation of what python does differently when running with the -O or optimize flag.

Answer 1

As answered in python optimization mode:

python -O does the following currently:

• completely ignores asserts
• sets the special builtin name __debug__ to False (which by default is True)

and when called as python -OO

• removes docstrings from the code

I don't know why everyone forgets to mention the __debug__ issue; perhaps it is because I'm the only one using it :) An if __debug__ construct creates no bytecode at all when running under -O, and I find that very useful.