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Postings from December 2021
On Tue, Dec 07, 2021 at 12:28:20AM +0000, Paul "LeoNerd" Evans wrote:
> I now have a partial attack on this, on a branch
>
> https://github.com/leonerd/perl5/tree/no-snails
> Actually rather than a tied array (because tie is so annoying to create
> from inside core), I just created a new kind of magic; "forbid" magic.
> This totally disallows any kind of access - all of its magic vtable
> calls immediately croak.
That's a better solution than mine.
> And already this code has caught something. I can't even build perl
> right now, because the build system makes miniperl and then uses
> miniperl to build the unicore tables, getting as far as:
>
> ./miniperl -Ilib lib/unicore/mktables -C lib/unicore -P pod -maketest -makelist -p
> Access to the @_ variable is forbidden (lenmagic) at lib/unicore/mktables line 1983.
> make: *** [makefile:408: uni.data] Error 25
>
> Hah! It really works :)
Nice.
> Lets peek at the source code:
>
> 1883 sub set_access($name, $field, @accessors) {
> ...
> 1983 if (grep { /^a/i } @_
> 1984 or length($access) > length('readable_'))
>
> Inside a real signatured sub, we already have code that tries to access
> @_. Oops.
>
> I suspect this code is supposed to read one of
>
> if(grep { /^a/i } @accessors
>
> or
>
> if(grep { /^a/i } ($name, $field, @accessors)
>
> but I can't immediately tell from context which. Perhaps someone
which is interesting, because effectively this new strictness has found
a bug.
(Rather than a missing feature - this isn't about the value of scalar @_
to determine how many arguments were passed/which are defaults)
Nicholas Clark
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