No.

You need to declare the hash before you try to use it.

This will work:

# hash declaration

# sub declarations

# call some sub that uses the hash
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This will not work:

# call some sub that uses the hash

# hash declaration

# sub declarations
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If you want to experiment with this on your own, move all of the code into individual subroutines and call them from main():

# declare this as a file-scoped lexical
my %Op;

main();

# subs follow

sub main
{
    assign_to_Op();
    do_something_else();
}

sub assign_to_Op
{
   %Op = ( ... );
}

sub do_something_else
{
    my $code = $Op{ ... };
    $code->();
}
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