Re^2: hash dereferencing issue with perl 5.16.3

In more modern Perls, you have the following syntactic options for dereferencing the hash reference:
my $lValue = ${$lHashRef}{'a'};
my $lValue = $$lHashRef{'a'};
my $lValue = $lHashRef->{'a'};
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I never use the first of these so cannot comment on that. However, my recollection of the second and third options is that both were available to use last millennium and probably in any version of Perl5. I'm not sure that these are best described as "more modern" these days and think it would be fair to say that use of this syntax would be perfectly valid in any perl likely to be encountered in production today.

All this is just for clarity of course and I fully endorse and agree with the rest of your post.

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Re^3: hash dereferencing issue with perl 5.16.3 by AnomalousMonk (Archbishop) on May 02, 2015 at 17:50 UTC
`${$lHashRef}{'a'}` is just the "canonical" version of `$$lHashRef{'a'}`. In the former syntax, `$lHashRef` can be replaced by any expression that evaluates to a hash reference. In the latter syntax, thorny issues of precedence arise if `$lHashRef` is replaced by anything other than another scalar hash reference. `c:\@Work\Perl\monks>perl -wMstrict -le "my $s = undef; my $t = 0; my $u = { qw(a aye b bee) }; ;; print ${ $s \|\| $t \|\| $u }{a}; " aye` [download] Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]

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Re^3: hash dereferencing issue with perl 5.16.3
by AnomalousMonk (Archbishop) on May 02, 2015 at 17:50 UTC

${$lHashRef}{'a'} is just the "canonical" version of $$lHashRef{'a'}. In the former syntax, $lHashRef can be replaced by any expression that evaluates to a hash reference. In the latter syntax, thorny issues of precedence arise if $lHashRef is replaced by anything other than another scalar hash reference.

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = undef;
 my $t = 0;
 my $u = { qw(a aye  b bee) };
 ;;
 print ${ $s || $t || $u }{a};
"
aye
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Give a man a fish: <%-(-(-(-<

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