Is postderef syntax on hashes supported?

Question

Let's say I have

my %foo;

Can I set keys foo, bar, baz to a b c by taking a slice and doing parallel assignment with postfix notation?

%foo->@{qw/foo bar baz/} = qw/a b c/

I used this syntax and I was told it was only "accidentally working". I don't see it generating a warning, and I also don't see it documented anywhere. Is this behavior supported or not?

Answer 1

The left side of -> is supposed to be an expression that returns a reference. Use anything else at your own risk.

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%foo->{a} used to work.

$ 5.10t/bin/perl -e'my %foo; %foo->{a} = 1; print "ok\n";'
ok

This was deemed to be bug.

$ 5.12t/bin/perl -e'my %foo; %foo->{a} = 1; print "ok\n";'
Using a hash as a reference is deprecated at -e line 1.
ok

$ 5.20t/bin/perl -e'my %foo; %foo->{a} = 1; print "ok\n";'
Using a hash as a reference is deprecated at -e line 1.
ok

$ 5.22t/bin/perl -e'my %foo; %foo->{a} = 1; print "ok\n";'
Can't use a hash as a reference at -e line 1.

There's no reason to believe %foo->@{...} is any more valid than %foo->{...}.

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Bug reported.