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Re: [perl #132142] Bleadperl v5.27.3-34-gf6107ca24b breaksMLEHMANN/AnyEvent-HTTP-2.23.tar.gz

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From:
Dave Mitchell
Date:
July 22, 2018 15:36
Subject:
Re: [perl #132142] Bleadperl v5.27.3-34-gf6107ca24b breaksMLEHMANN/AnyEvent-HTTP-2.23.tar.gz
Message ID:
26227_1532273804_5B54A488_26227_18_1_20180722153624.GB2750@iabyn.com
On Sun, Jul 22, 2018 at 04:28:36PM +0200, Andreas Koenig wrote:
> The point is that it is not only user-visible but actually user-tunable.
> Your arguments about not having user-visible effects collapse under
> these figures. What sense does it make to implement and announce an
> optimization that in fact requires cooperation from the user and then
> not to document it? And then to claim that it is intended as being
> non-user-visible?

Most optimisations I do are "user tunable" by that definition.

Did you know that if you do $a + $b, and ensure that $a and $b have only
ever contained integers (so for example have never held strings or been
used in a string context) then the addition is a lot faster? Is that
documented in perlop?  No. It is documented in perldelta? Quite possibly,
in the "Optimizations" section for whatever release I tweaked pp_add() et
al.

I think the position you have taken is extreme, and if we used that
position to inform future perl bug fixes, perl would development would
come to a complete halt. 

Really I am utterly confounded by the stance you are taking. Perl has a
strong ethos of maintaining backwards compatibility where reasonable, to
the extent that many many people shout at us for causing the stagnation of
perl 5. But we have never committed to maintaining 100% backwards
compatibility at all costs. Each decision is made on its own merits, with
a big dose of pragmatism.

As I have said before, I am willing to debate the pragmatic pros and cons
of whether it is better to make this change in behaviour. What I am not
prepared to accept, is that digging out a 14 year old RT ticket, which at
no no point proposes that weak references should be preserved, has somehow
bound us in perpetuity to preserve weak references.

-- 
Indomitable in retreat, invincible in advance, insufferable in victory
    -- Churchill on Montgomery

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