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Re: [perl #76438] peephole optimiser could prune more dead code

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July 15, 2010 01:31
Re: [perl #76438] peephole optimiser could prune more dead code
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On 15 July 2010 01:12, Dave Mitchell <> wrote:
> On Wed, Jul 14, 2010 at 09:39:35AM +0200, demerphq wrote:
>> Whomever decided that
>>   $a . $a
>> is specified when $a is tied and returns a different value each fetch
>> had forgotten this fact.
> You'll have to argue that with Hugo then!
> commit 8d6d96c1bf85fd984f18f84ea834be52b168c812
> Author:     Hugo van der Sanden <>
> AuthorDate: Sat May 26 18:05:12 2001 +0100
> Commit:     Jarkko Hietaniemi <>
> CommitDate: Sat May 26 22:31:46 2001 +0000
>    Re: 5.6.*, bleadperl: bugs in pp_concat
>    Message-Id: <>

I'm not sure what your point is? Simply because Hugo wrote/pushed a
patch that somehow proves something? I don't think so. Just because a
commiter didn't think through the full ramifications of a patch, or
even knew of the ramifications but still went through with it on the
grounds of providing "least worst" behaviour doesn't make that patch
law over long existing documentation.

The documentation for ++ is pretty clear.

If the concatenation of a tied variable that mutates is well
specified, then it would mean that one can take a construct documented
to have unspecified behaviour wrap it up in a tie to resolve the
unspecifiedness, which seems to me to be simply absurd.

Thus the onus is not on me to show why this is unspecified, as the
docs say it is, the onus instead is on those who disagree with the
documentation to find a way to get out of this logical absurdity.

I have to say that I'm struggling to see why what you just posted
doesn't essentially boil down to a position that the docs are
meaningless and that whatever is committed is right. If so then you
might as well stop fixing those "bugs" as they aren't really "bugs"
then are they? I'm pretty sure you don't think this, so why do you
think that this patch is different?

perl -Mre=debug -e "/just|another|perl|hacker/"

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