[Python-ideas] Allow additional separator character in variables

[Stephan Houben]

There is an unfortunate ambiguity in using a character that means "not" as
a word separator:

  nuke.do¬launch()

"But... I called the method which explicitly did *not* launch the nuke!"

Stephan

Op 19 nov. 2017 11:05 schreef "Steve Barnes" <gadgetsteve at live.co.uk>:



On 19/11/2017 05:01, Nick Timkovich wrote:
> Python does not use U+2010 HYPHEN for the minus operator, it uses the
> U+002D (-) HYPHEN-MINUS.
>
> In some monospace fonts, there is a subtle difference between U+002D,
> U+2013 EN DASH, and U+2014 EM DASH, but it's usually hard to tell them
> *all* apart.
>
> If you want to make a proposal, I'd suggest that you limit it to
> allowing the U+2010 HYPHEN to be used for names. U+002D simply cannot be
> changed because it would break billions of lines of code.
>
> On Sat, Nov 18, 2017 at 10:44 PM, Mikhail V <mikhailwas at gmail.com
> <mailto:mikhailwas at gmail.com>> wrote:
>
>     On Sun, Nov 19, 2017 at 3:42 AM, Nick Coghlan <ncoghlan at gmail.com
>     <mailto:ncoghlan at gmail.com>> wrote:
>
>     > For anyone tempted to suggest "What about multiple underscores
>     > indicating continuation of the variable name?", that's still a
>     > compatibility problem due to the unary minus operator:
>     >
>     >     >>> my--variable
>     >     2
>     >     >>> my---variable
>     >     0
>
>     That seems to be another showcase of misfotune that Python
>     uses hyphen for minus operator. I know it is not language designer's
>     fault, because basic ASCII simply did not not include minus character.
>     But do you realise that the **current** problem you are adressing is
>     that
>     font designers forgot to make the minus character (in monospaced font)
>     distinctive from the hyphen character?
>
>     Well, what can I say, I just think it should be a reason to make a
>     collective complain to font providers, but not that you should
silently
>     accept this and adopt the language design to someone's sloppy font
>     design.
>
>     As an aid for monospace die-hards, to minimise the confusion one could
>     publish a style-guide that recommends to disclose the minus operator
>     (currently
>     hyphen char)  in spaces, like a - b, and probably disallow the new
>     proposed
>     hyphen character in the beginning of the identifiers.
>     That would still leave potential for confusion because you cant'
>     force everyone
>     to follow style-guides, but one should struggle to break from this
>     cycle anyway.
>
>     >
>     > Would hyphens in variable names improve readability sometimes?
>
>     For reading code, indeed, always and very much. Of course not in case
>     I would be forced
>     to use monospaced font with a similar minus and hyphen. But
>     in that case I am already accepting the level of readability of
>     12th century, so this would not make things much worse, and I
>     would simply put spaces around the minus operator and try to highlight
>     it with some strong color.
>
How about allowing ¬, (ASCII 172, U+00ac, NOT sign), in variable names
as in my¬variable - it has the advantages that:

  - it is visually distinguishable even in mono-spaced fonts,
(personally I use mono-spaced all of the time when programming but I
know that I am a dinosaur),
  - is actually on many keyboards as a single character, (I don't know
of any which actually produce different characters for minus on the
numeric keypad and hyphen elsewhere), so can be typed as a single key press,
  - Is generally unused AFAIK other than in papers about logic,
  - It is currently unused in the Python language.

This might upset some who would like use it to replace the unary not
operator but I suspect that it would be far fewer people than the
potential breakages discussed so far.

--
Steve (Gadget) Barnes
Any opinions in this message are my personal opinions and do not reflect
those of my employer.

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