[Python-ideas] Have a "j" format option for lists

Steven D'Aprano steve at pearwood.info
Wed May 9 20:45:14 EDT 2018

On Wed, May 09, 2018 at 04:56:38PM -0300, Facundo Batista wrote:
> 2018-05-09 13:48 GMT-03:00 Rhodri James <rhodri at kynesim.co.uk>:
> > -1 until you give me an actual spec rather than a curious example.
> >
> > Sorry if that sounds a bit rude, but I spend most of my time trying to find
> Be sorry, it was rude.

I do not agree that Rhodri's comments were rude. They were frank and 
honest constructive criticism of the presentation of your idea.

I have no patience with hair-trigger accusations of "rudeness" as a 
debating tactic to curtail criticism, and your response to Rhodri's mild 
and fair words looks exactly like that. Whether you intended it that way 
or not, that is what it looks like to me.

I too spent some time scratching my head trying to guess what you expect 
this "j" format code to do, including the fundamental question "why j 
and not some other letter?". Even after I worked out some of it, I was 
still left with questions. So I think that Rhodri's criticism is 
completely valid: your post was vague, with a lack of detail and not 
even an attempt to provide a partial specification.

That doesn't have to be a formal specification, but it should be at 
least an attempt to say "this is what the format code means", rather 
than expect people to guess from a single example.

(By the way, if you answered my earlier questions, I haven't seen the 

Dealing with under-specified, vague instructions, and the invariable 
failure to guess correctly what was intended, is frustrating, annoying 
and painful. We should not be surprised that vague proposals can trigger 
an angry response, but Rhodri's post showed great restraint.

It isn't just the waste of time and effort when when we guess wrong, it 
is also the implied disrespect: "I am too important to bother explaining 
myself to minions like you. Work out what I mean."

If an idea is important enough to post here, we should be willing to 
spend some time presenting the idea in sufficient detail so that people 
don't have to guess what we mean. As the Zen says, "Explicit is better 
than implicit".

No, that doesn't mean that we have to write a PEP before posting. There 
is a middle-ground between giving a single example and expecting people 
to extrapolate from it, and writing a full PEP.


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