[Python-ideas] Add \e escape code

[M.-A. Lemburg]

On 11.06.2013 20:36, Chris Angelico wrote:
> On Wed, Jun 12, 2013 at 4:16 AM, M.-A. Lemburg <mal at egenix.com> wrote:
>> How would you add a new escape character in a backwards compatible
>> way ?
>>
>> Adding new escape characters is not easy, since Python defaults
>> to passing them through as-is, e.g. '\e' == '\\e'.
> 
> My understanding of [1] is that the feature of keeping them unchanged
> is meant to be a debugging aid, not something you depend on. Use of
> unescaped backslashes in non-raw string literals is already dangerous
> to editing (if someone changes your Windows path name to c:\testing,
> your code is broken). If a new version breaks someone's non-raw
> literal "c:\everything", it was already broken.
> 
> [1] http://docs.python.org/3/reference/lexical_analysis.html#literals

I'm not saying that it's useful to rely on Python's behavior,
only that any such change has the potential to break perfectly
working code.

The last time we changed the escape code was for the introduction
of Unicode string literals. That was 13 years ago. And we carefully
checked what other languages were using for Unicode at the time.

Given that \e only saves you two key strokes (\033 and
\x1b are the usual ways to write ESC in ASCII strings),
I think the ratio between usefulness and potential breakage
is not in favor of an addition.

BTW: pylint detects such unsupported escape codes:

http://docs.pylint.org/features.html?highlight=w1401#string-constant-checker

-- 
Marc-Andre Lemburg
eGenix.com

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