On 04Aug2019 2122, raymond.hettin...@gmail.com wrote:
We should revisit what we want to do (if anything) about invalid escape
sequences.
For Python 3.8, the DeprecationWarning was converted to a SyntaxWarning which
is visible by default. The intention is to make it a SyntaxError in Python 3.9.
This once seemed like a reasonable and innocuous idea to me; however, I've been
using the 3.8 beta heavily for a month and no longer think it is a good idea.
The warning crops up frequently, often due to third-party packages (such as
docutils and bottle) that users can't easily do anything about. And during
live demos and student workshops, it is especially distracting.
I now think our cure is worse than the disease. If code currently has a non-raw
string with '\latex', do we really need Python to yelp about it (for 3.8) or
reject it entirely (for 3.9)? If someone can't remember exactly which special
characters need to be escaped, do we really need to stop them in their tracks
during a data analysis session? Do we really need to reject ASCII art in
docstrings: ` \-------> special case'?
IIRC, the original problem to be solved was false positives rather than false
negatives: filename = '..\training\new_memo.doc'. The warnings and errors
don't do (and likely can't do) anything about this.
I broadly agree that the warning is very annoying, particularly when it
comes from third-party packages (I see it from some of pip's vendored
dependencies all the time), though I do also see many people bitten by
FileNotFoundError because of a '\n' in their filename.
Raymond - a question if I may. How often do you see these occurring from
docstrings, compared to regular strings?
I feel like I only ever see the irrelevant warnings being raised from
docstrings, so if others confirm this perhaps there's a way we could
suppress the warnings where the string is the entire expression?
Cheers,
Steve
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