Re: Dereference of undefined value OK under strictures?

My guess is auto vivification

$ perl -wMstrict -le 'sub foo { return @_; }
 ;;
 my $ar;
 print foo(@$ar);
 print $ar;'

ARRAY(0xada8b410)
$
[download]

The aliasing is bypassing the strict check.

Something like this at least ... ;)

Update

  DB<12> use strict;print  @$b
Can't use an undefined value as an ARRAY reference at (eval 39)[/data/
+data/com.termux/files/usr/lib/perl5/5.28.2/perl5db.pl:738] line 2.

  DB<13> use strict;print  @$b=(1..3)
123
  DB<14> p $b
ARRAY(0xb0a92180)
  DB<15>
[download]

I wasn't too wrong, strict tolerates it as long as it is an lvalue. And aliasing seems to have this effect.

HTH! :)

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

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Re^2: Dereference of undefined value OK under strictures? by AnomalousMonk (Archbishop) on Jun 28, 2019 at 21:28 UTC
... auto vivification ... strict tolerates it as long as it is an lvalue ... aliasing seems to have this effect. Ah, yes! And now that you mention it, I vaguely remember a previous discussion along these lines. Thanks! Give a man a fish: `<%-{-{-{-<`	[reply] [d/l]
Re^3: Dereference of undefined value OK under strictures? by Anonymous Monk on Jun 28, 2019 at 22:09 UTC
for ex map() and grep() suppress "Can't use an undefined value as an ARRAY reference at ..." errors... autoviv happens in lvalue context and perls built ins arent always consistent	[reply]
Re^2: Dereference of undefined value OK under strictures? by afoken (Chancellor) on Jun 30, 2019 at 11:05 UTC
`DB<12> use strict;print @$b Can't use an undefined value as an ARRAY reference at (eval 39)[/data/ +data/com.termux/files/usr/lib/perl5/5.28.2/perl5db +.pl:738] line 2. DB<13> use strict;print @$b=(1..3) 123 DB<14> p $b ARRAY(0xb0a92180) DB<15>` [download] Using `$a` or `$b` triggers a special case for sort. This can be seen by using some other variable name instead: >perl -w -Mstrict -E 'say @$b' Can't use an undefined value as an ARRAY reference at -e line 1. >perl -w -Mstrict -E 'say @$c' Global symbol "$c" requires explicit package name (did you forget to d +eclare "my $c"?) at -e line 1. Execution of -e aborted due to compilation errors. >perl -w -Mstrict -E 'say @$b=(1..3)' 123 >perl -w -Mstrict -E 'say @$c=(1..3)' Global symbol "$c" requires explicit package name (did you forget to d +eclare "my $c"?) at -e line 1. Execution of -e aborted due to compilation errors. > [download] Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re^3: Dereference of undefined value OK under strictures? by LanX (Saint) on Jun 30, 2019 at 12:35 UTC
Yes I kept it short, but what's your point? We are testing against `strict` refs not vars. `$ perl -w -Mstrict -E 'my $c; say @$c' Can't use an undefined value as an ARRAY reference at -e line 1. $ perl -w -Mstrict -E 'my $c; say @$c=(1..3)' 123 $` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply] [d/l]