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by TuxSH 618 days ago
"except:" is explicit enough and "except BaseException" is redundant.

Moreover I think there is a real risk people are going to write "except Exception:" instead, which breaks in the fringe case an exception that derives from BaseException (enforced by interpreter) but not from Exception is thrown.

Even if catch Exception is what users usually mean, changing code from "catch (BaseException):" to "catch Exception:" may break some code if improperly reviewed.

It's also not worth breaking production code over this.
2 comments
williamsmj 618 days ago
> "except:" is explicit enough and "except BaseException" is redundant.

Take that up with the consensus view of the python community, as reflected by python linters in their default configuration, almost all of which warn on bare except.

The debate in the PEP is whether this should be a syntax error. The debate about whether it is good style is over though.

> It's also not worth breaking production code over this.

Agreed.

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TuxSH 618 days ago
> Take that up with the consensus view of the python community, as reflected by python linters in their default configuration, almost all of which warn on bare except.

I don't fully agree on it being a purely a style issue (though the warnings from linters are wholly justified). From what I understand, "except:" is a code smell because you don't actually want to catch BaseException instead of just Exception.

Linters wouldn't have warned about it if it meant "except Exception:". The real issue, IMO, is the fact non-exceptions (Ctrl-C, generator exit, program exit code, etc.) have been crammed into the exception system.

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zahlman 618 days ago
>which breaks in the fringe case an exception that derives from BaseException (enforced by interpreter) but not from Exception is thrown.

For many users, in many cases, this would be fixing the code rather than breaking it.

Forcing people to write either `except BaseException:` or `except Exception:` means forcing them to think about which one they actually mean. This is a good thing, just like the enforcement of proper separation between bytes and text is a good thing.

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