[Python-ideas] Compact repr operator (i.e., __short_repr__)

[Mahmoud Hashemi]

Roundtrippable reprs are certainly part of Python canon, whether or not
they are universally used (Chris), or guaranteed (Mike).

I could see __short_repr__ (and associated reprlib) being the desired
behavior in some console environments, but I'm not one to say it should be
the default in the main Python REPL.

My use cases are for 1) a web based console/REPL and 2) a configuration
store that maintains a human readable history of past values (i.e., it does
not maintain references to the objects themselves).

But mostly I wanted to kick off the discussion of how to update reprlib
(and pprint) to be more efficient and applicable.

Mahmoud



On Mon, Feb 8, 2016 at 4:28 PM, Michael Selik <mike at selik.org> wrote:

> On Mon, Feb 8, 2016 at 6:36 PM Mahmoud Hashemi <mahmoud at hatnote.com>
> wrote:
>
>> Without something like this, there's no way to ask an object if it's repr
>> is of manageable length, or how its repr could be meaningfully shortened.
>> Usually I just chop out the middle and add an ellipsis, but as for the time
>> spent generating that middle, I'll never get those cycles back.
>>
>
> With the addition of ``__short_repr__`` would there be a change to the
> default Python REPL? If not, how would you use the new magic method? If so,
> then why not just change __repr__ for all the built-ins to truncate
> automatically? As far as I know, reprs are not part of the backwards
> compatibility guarantee. (Note, I'm not advocating for changing reprs.)
>
> If the usage would be to write a function that checks for the existence of
> __short_repr__, then why not simply move the implementation of ``if len(s)
> < maxlen`` etc. to that function?
>
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