Experimental keys on scalar is now forbidden

Question

I am trying to debug a Perl script that is giving me the error

Experimental keys on scalar is now forbidden

This seems to be an issue my system having a newer version of perl, but was hoping some can sugegst a quick fix.

The line in question is

foreach my $elemName(keys $grammar -> {$groupName})

grammer was defined as

my $grammar = {};

and groupName comes from

foreach my $groupName (keys %$grammar)

I do not know much about perl, so any help would be appreciated

I have a similar issue with this line

push($DbRef->{def_param}{$par_descr}->{dataset}, $blkDs);

with error Experimental push on scalar is now forbidden ... near "$blkDs)"

I have tried some solutions I have found about dereferencing, but the syntax is very confusing to me.

Answer 1

keys EXPR and push EXPR, LIST were introduced in 5.14 as an experimental feature.

keys EXPR and push EXPR, LIST started warning in 5.20 when the concept of warnings for experimental features was introduced.

keys EXPR and push EXPR, LIST were removed in 5.24 as the experiment was deemed a failure. (The design of keys EXPR is fundamentally flawed.)

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To get the keys of hash, you can use keys %NAME. You can also use a hash deference, such as keys %BLOCK or keys EXRP->%*.

To get the indexes of an array, you can use keys @NAME. You can also use an array deference, such as keys @BLOCK or keys EXRP->@*.

To push scalars onto an array, you can use push @NAME, LIST. You can also use an array deference, such as push %BLOCK, LIST or push EXRP->@*, LIST.

---

In your case, you want

keys %{ $grammar -> {$groupName} }

or

keys $grammar -> {$groupName} -> %*   # 5.24+

and

push(@{ $DbRef->{def_param}{$par_descr}->{dataset} }, $blkDs);

or

push($DbRef->{def_param}{$par_descr}->{dataset}->@*, $blkDs);   # 5.24+