[Python-Dev] Re: Call for defense of @decorators (original) (raw)

Tim Peters tim.peters at gmail.com
Fri Aug 6 18:06:49 CEST 2004

[Barry Warsaw]

So I spent a little time futzing with python-mode and some of my decorator code, to try some alternative leading characters. Of the ones that cannot be used in valid Python code today (i.e. no backward compatibility issues), I tried ':', '/', '=', '*', and '|'.

: wasn't bad, and it had some nice symmetry with the function definition that follows. But those two little dots can be hard to read in some fonts ...

Indeed! I read that paragraph four times before I realized it started with a colon -- a fleck of dirt on the screen obscured it completely.

/ and | also weren't bad, although bar is probably preferred.

Ya, but then we preclude adding the unary-pipe operator. This is very important for numeric types that need to implement half the absolute value:

|3 1.5 |-3 1.5

...

Someone else pointing out that the bar kind of looks like it's anchoring the decorator to the function, and I got a similar sense of that.

OK, seriously, me too.

... In summary, I can definitely sympathize with the concern of tool authors who have settled on @ as a meta-character that Python will not use.

Yup.

I wonder how the Leo or ipython folks would feel if the only change to the current implementation of PEP 318 was to change the decorator introducing character. If we can increase the community's consensus by making this little change, I wouldn't oppose it.

Me neither.

My preference then would be to use = with | and : as alternatives, in that order.

Same here, except -1 on the colon. Although = would preclude introducing the unary-equals operator, which is very important for numeric types that need to implement the absolute value rotated by 90 degrees.

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