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Postings from May 2004
On May 21, 2004, at 17:47, Rafael Garcia-Suarez wrote:
> If you look at what contexts permit and forbid autovivification, you'll
> see that the situation in perl is currently complex and probably not
> very consistent. Anyway, in general lvalue contexts don't permit it; a
> lexical declaration can be seen as this; and you still can write, in a
> rather obfuscated way,
>
> (my $x = {}) -> {foo}
>
> Your patch looks correct at a first glance, but I'm not very inclined
> to
> apply it, unless the crowd comes up with good reasons why to.
Speaking of autovivification, how about such cases in reverse, That is,
when non-reference value is assigned with --, ++, +=, etc ? i.e.
perl -le '$x = {}; print ++$x'
You may expect '1' but this prints a random number, or numified version
of "HASH(0xdeadbeef)" plus 1. While this makes sense to those who
knows camel anatomy, this is somewhat asymmetrical and confusing....
[A few minutes later...]
Hey, watch this!
> % perl -le 'my $x=42; $x->[0]=3.14; print $x; print $x->[0]; print
> ref($x)'
> 42
> 3.14
>
> % perl -le 'my $x; $x->[0] = 3.14; print $x; print $x->[0]; print
> ref($x)'
> ARRAY(0x801180)
> 3.14
> ARRAY
See the difference? The first one has 42 assigned a priori. I have
duplicated this even on good old 5.00503, not to mention 5.8.4.
Dan the Camel (?:Ab)user
P.S. I found more of Hawakawa-kun's my abuses at
http://shibuya.pm.org/slides/bkcon2004/hayakawa.pdf
I only hope you don't do that in your PRODUCTION CODES....
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