[Python-Dev] PEP 553; the interaction between $PYTHONBREAKPOINT and -E

[Barry Warsaw]

Victor brings up a good question in his review of the PEP 553 implementation.

https://github.com/python/cpython/pull/3355
https://bugs.python.org/issue31353

The question is whether $PYTHONBREAKPOINT should be ignored if -E is given?

I think it makes sense for $PYTHONBREAKPOINT to be sensitive to -E, but in thinking about it some more, it might make better sense for the semantics to be that when -E is given, we treat it like PYTHONBREAKPOINT=0, i.e. disable the breakpoint, rather than fallback to the `pdb.set_trace` default.

My thinking is this: -E is often used in production environments to prevent stray environment settings from affecting the Python process.  In those environments, you probably also want to prevent stray breakpoints from stopping the process, so it’s more helpful to disable breakpoint processing when -E is given rather than running pdb.set_trace().

If you have a strong opinion either way, please follow up here, on the PR, or on the bug tracker.

Cheers,
-Barry

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