[Python-Dev] Re: [Patches] [Patch #101175] Fix slight bug in the Ref manual docs on listcomprehensions

[Tim Peters]

[Tim]
>> Guido hates it *because* it's almost certainly an error.

[Greg Ewing]
> Yes, I know what you meant. I was just trying to point out
> that, as far as I can see, it's only Guido's *opinion* that
> it's almost certainly an error.

Well, it's mine too, but I always yield to him on stuff like that anyway;
and I guess I *have* to now, because he's my boss <wink>.

> Let n1 be the number of times that [x if y] appears in some
> program and the programmer actually meant to write something
> else. Let n2 be the number of times [x if y] appears and
> the programmer really meant it.
>
> Now, I agree that n1+n2 will probably be a very small number.
> But from that alone it doesn't follow that a given instance
> of [x if y] is probably an error. That is only true if
> n1 is much greater than n2, and in the absence of any
> experience, there's no reason to believe that.

I argued that one all I'm going to -- I think there is.

>> ... The *intent* here is to supply a flexible and highly expressive
> way to build lists out of other sequences; no other sequences, use
> something else.

> That's a reasonable argument. It might even convince me if
> I think about it some more. I'll think about it some more.

Please do, because ...

>> if you choose not to do the work anymore, you took yourself out
>> of the loop.

> You're absolutely right. I'll shut up now.

Please don't!  This patch is not without opposition, and while consensus is
rarely reached on Python-Dev, I think that's partly because "the BDFL ploy"
is overused to avoid the pain of principled compromise.  If this ends in a
stalement among the strongest proponents, it may not be such a good idea
after all.

> (By the way, I think your mail must have gone astray, Tim --
> I don't recall ever being offered ownership of a PEP, whatever
> that might entail.)

All explained at

    http://python.sourceforge.net/peps/

Although in this particular case, I haven't done anything with the PEP
except argue in favor of what I haven't yet written!  Somebody else filled
in the skeletal text that's there now.  If you still want it, it's yours;
I'll attach the email in question.

ok-that's-16-hours-of-python-today-in-just-a-few-more-i'll-
    have-to-take-a-pee<wink>-ly y'rs  - tim


-----Original Message-----

From: Tim Peters [mailto:tim_one@email.msn.com]
Sent: Wednesday, July 26, 2000 1:25 AM
To: Greg Ewing <greg@cosc.canterbury.ac.nz>
Subject: RE: [Python-Dev] PEP202


Greg, nice to see you on Python-Dev!  I became the PEP202 shepherd because
nobody else volunteered, and I want to see the patch get into 2.0.  That's
all there was to it, though:  if you'd like to be its shepherd, happy to
yield to you.  You've done the most to make this happen!  Hmm -- but maybe
that also means you don't *want* to do more.  That's OK too.